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Progress Toward Restoring the Everglades: The Second Biennial Review - 2008 (2008)

Chapter: 5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem

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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 145
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 146
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 152
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 153
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 154
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 155
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 157
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 158
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 159
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Page 160
Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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Suggested Citation:"5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem." National Research Council. 2008. Progress Toward Restoring the Everglades: The Second Biennial Review - 2008. Washington, DC: The National Academies Press. doi: 10.17226/12469.
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5 Lake Okeechobee and Its Place in the Restoration of the South Florida Ecosystem Lake Okeechobee (Figure 5-1) is at the heart of the hydrologic system, with connections to the east and west coasts as well as downstream to the southern Everglades. The lake was a critical part of the pre-drainage hydrology because it was a primary storage mechanism that modulated downstream flows by stor- ing water in wet years and gradually releasing water during dry periods. After artificial connections to the St. Lucie Canal to the east and the Caloosahatchee River to the west, with a dike around its perimeter, the lake became a diversion point. Large amounts of water that once flowed southward were instead diverted to the ocean, and the lake became much less of a controlling factor for down- stream flows to the south, while large, fluctuating flows to the Caloosahatchee and St. Lucie estuaries and the Lake Worth Lagoon have had adverse impacts on them (see Figure 5-2). In addition, the lake’s water quality has been degraded by the external loading of nutrients, especially phosphorus (Engstrom et al., 2006). As a result, although the lake is the largest potential natural source of storage for water in the system, its water cannot be delivered to the often-parched remnant Everglades ecosystem because today’s stormwater treatment areas (STAs) do not have the capacity to treat increased volumes of nutrient-enriched water. Changes in water quantity and degradation of water quality (Havens and Gawlick, 2005; Johnson et al., 2007) have also adversely affected the lake’s ecological value as a habitat for diverse biotic communities as well as the lake’s recreational value. As in many other complex water management problems (Alexander et al., 2007; Feldman, 2008), extensive research on the lake makes clear that water quantity and quality are inseparably intertwined and need to be considered together in planning and implementing restoration plans (James and Havens, 2005; RECOVER, 2007c). For example, increases in water level (quantity) directly affect the amount of submerged aquatic vegetation (SAV), which in turn allows phosphorus-rich sediments to be mobilized into the water column (quality) (Johnson et al., 2007). Although for organizational reasons water quantity and 143

144 Progress Toward Restoring the Everglades Littoral Zones Lake Okeechobee Everglades Agricultural Area FIGURE 5-1  Lake Okeechobee. Figure 5-1.eps bitmap with vector type & rules SOURCE: Adapted from http://www.evergladesvillage.net/sat/everglades/thumbs.html. © Inter- national Mapping Associates. quality are considered separately in places in this chapter, readers should keep their close connection in mind. This chapter explores several facets of the management of Lake Okeechobee and the potential role it might play in the Everglades restoration. The chapter also includes a discussion of the downstream effects of the disturbed lake, including

Lake Okeechobee 145 FIGURE 5-2  Lake Okeechobee within the South Florida ecosystem. © International Mapping Associates. Figure 5-2.eps bitmap impacts on the estuaries that receive direct flows from it. Allowing the lake to function as the heart of the Everglades as it used to in the pre-drainage system requires large additional restoration efforts. Therefore, the final section of the chapter addresses current and proposed restoration efforts and discusses addi- tional options for restoring the system.

146 Progress Toward Restoring the Everglades THE CONDITION OF LAKE OKEECHOBEE Lake Okeechobee presently is plagued by both high and, more recently, very low water levels as well as poor water quality. These conditions have adversely affected the lake’s structure and functioning. Water Quantity Lake Okeechobee receives most of its inflow from Central Florida via the flows of the Kissimmee River. Until the late 1800s and early 1900s, no canals connected the lake to the Caloosahatchee or St. Lucie estuaries to the west and east, respectively (Blake, 1980; Brooks, 1974; Parker, 1974, Parker et al., 1955). In the rainy season, the lake levels sometimes increased to 21 or 22 feet above mean sea level, and lake waters also flowed southward through the central body of the Everglades via overland flow when the lake exceeded these levels (USACE, 1999). In rainy periods, some lake water also flowed west through wetlands into Lake Hicpochee, which served as the headwaters of the Caloosahatchee (Steinman et al., 2002a). Thus, the lake was a major source of water storage and supply for the entire Everglades ecosystem during periods of high water. Also, the lake, its watershed to the north, and the ecosystem to the south transmitted water fairly slowly. As a result, the seasonality of water level fluctuations in the lake and its watershed and the severity of most dry and wet periods in the ecosystem was considerably reduced compared to today’s system (Beissinger, 1986; NRC, 2005). The condition of Lake Okeechobee today differs distinctly from its histori- cal condition. Lake Okeechobee has undergone major modifications; primary among these was diking that began with a small earthen dike in the 1910s, was expanded in the 1930s along the south shore of the lake, and gradually strengthened until the current Herbert Hoover Dike was completed in the 1960s (Blake, 1980; Brooks, 1974; Parker, 1974, Parker et al., 1955). The construction of the dike restricted the ability of the lake to expand in response to wet periods and reduced the total storage capacity of the lake. Today, the lake functions as a regional reservoir whose inflows and outflows are regulated based on water supply, flood control, and environmental needs (see Box 5-1). The area of the lake varies from about 300,000 acres at its historical low water level to about 470,000 acres (more than 730 square miles) when water levels reach 20 feet above mean sea level. When the lake is at an elevation of 9 feet, a very low level, it contains about 1.75 million acre-feet (MAF) of water; at the upper end of current operating policy of 17 feet, storage is about 4.8 MAF. Each additional

Lake Okeechobee 147 22 20 Water level (ft above MSL) 18 16 14 12 10 8 1910 1930 1950 1970 1990 2010 Year FIGURE 5-3  Elevations of Lake Okeechobee surface 1912–2006. Figure 5-3.eps SOURCE: Daily water level data for April 12, 1912–May 22, 2008, accessed at http://waterdata. usgs.gov/nwis/nwisman/?site_no=02276400&agency_cd=USGS. foot of elevation above 17 feet adds about 425,000 to 525,000 acre-feet of s ­ torage, up to 26 feet elevation (Abtew et al., 2007). Natural lake functioning was also altered by the establishment of new con- nections to the east via the St. Lucie Canal and to the west via a canal to the Caloosahatchee River, and the construction of levees, water control structures, and locks (Rogers and Allen, 2008). Large releases of water that are frequently made through canals to the Caloosahatchee and St. Lucie estuaries during wet periods are adversely affecting the vitality of those ecosystems (as discussed later in this chapter). Water levels are currently maintained at much lower levels than historical levels. The U.S. Army Corps of Engineers (USACE) estimated that before the first dike was constructed, the lake had a mean stage of 20.5 feet (USACE, 1999), but today the USACE aims to maintain the water level at about a 12-foot elevation to protect the integrity of the Herbert Hoover Dike (USACE, 2006). A 1999 report showed that at an elevation of 18 feet, 3 of the 13 components of the dike are

148 Progress Toward Restoring the Everglades BOX 5-1 Average Annual Water Budget for Lake Okeechobee The lake is fed from several watersheds north and west of the lake and the Everglades Agricul- tural Area (EAA) (see Figure 5-2). Total stream-flow input to the lake averages 1.62 million acre-feet (MAF) (based on data between 1965–2000), with an addi­tional 1.67 MAF direct rainfall input resulting from an annual average rainfall of about 50 inches (4.2 feet) per year over the lake (see Figure 5-4). However, precipitation is more than offset by evapotranspiration, which amounts to 2.09 MAF per year. Not considering evapotranspiration, total outflow is 1.43 MAF, 29 percent of which is discharged to the Caloosahatchee River (as regulatory discharges and environmental releases), 12 percent to the St. Lucie River (as regulatory discharges and environmental releases), 7 percent to the lower east coast (as regulatory discharges), and 4 percent to the Water Conservation Areas (as regulatory discharges). Water supply applications (mostly agriculture) in these basins receive 38 percent of the outflows from Lake Okeechobee, and the remaining 10 percent is accounted for in other outflows. Inflows and outflows are highly variable within annual periods and from year to year. FIGURE 5-4  Average water balance of Lake Okeechobee based on the current Lake Okeechobee Figure 5-4.eps Regulation Schedule (LORS) and precipitation data from 1965–2000. bitmap NOTE: All flows are in thousands of acre-feet. Diagram depicts all flows greater than 0.1 percent of the total water budget (including evapotranspiration), with the exception of 141,000 acre-feet in “other outflows.” These other outflows include flow to small basins around the lake, the Seminole Tribe, and the Florida Power and Light Reservoir. SOURCE: Data from J. Obeysekera, SFWMD, personal communication (2008).

Lake Okeechobee 149 classified as hazardous, with high probabilities of failure; at 21 feet, 8 of the 13 are hazardous, with 4 having probabilities of failure of 0.89 or higher; and at 26 feet, 11 of the 13 are hazardous, with 7 virtually certain to fail (USACE, 1999). In 2000, the U.S. Congress authorized the USACE to rehabilitate the dike, and initial construction of a 4.6-mile section of the 140-mile-long dike began in 2005. Completion of all improvements is scheduled over a 25-year period (USACE, 2006), contingent on congressional appropriations. Water Quality Historically, water flowing into Lake Okeechobee came primarily from the Kissimmee River, whose extensive wetland floodplain filtered nutrients from the water. This kept nutrients at extremely low concentrations throughout the system, particularly with respect to phosphorus, the contaminant of greatest concern. The extensive spread of agriculture in the upstream drainage basins, plus the channelization of the river and the creation of canals conveying storm-water from agricultural areas directly to the lake, resulted in high phosphorus loads to the lake (Engstrom et al., 2006). A large proportion of phosphorus loaded to the lake accumulated in sediments. The role of phosphorus as a controlling factor in eutrophication of fresh- water ecosystems has been recognized for several decades. High phosphorus concentrations in the lake adversely impact biota by altering the structure and functioning of both the lake and downstream ecosystems. The overall increase of phosphorus loading in the past decades has resulted in conversion of a phosphorus-limited system to a nitrogen-limited system. This has resulted in many changes in the lake, including increased frequency of algal blooms and an increasing abundance of nitrogen-fixing cyanobacteria (Havens et al., 2007). Unless phosphorus in Lake Okeechobee’s water can be reduced, there are seri- ous constraints to discharging large volumes of water to the south for use in Everglades restoration. The phosphorus problem is exacerbated because much of the phosphorus accumulates in soils, ditches, wetlands, and lake bottoms where it can remain for a long time; such stored phosphorus is often referred to as legacy ­phosphorus. Legacy phosphorus is problematic both in the Lake Okeechobee watershed and in the lake itself, because the soil- and sediment-associated phosphorus can serve as steady sources of phosphorus to the water column. When it does so in the watershed, it contributes to the external phosphorus load to the lake; when it does so in the lake, it creates an internal phosphorus load to the lake water. The effects of legacy phosphorus on water quality can last several decades.

150 Progress Toward Restoring the Everglades External Phosphorus Loads Most of the current external phosphorus load to Lake Okeechobee comes from agricultural and urban activities in the watershed. Phosphorus is added to uplands in fertilizers, organic solids (e.g., sewage sludge, animal wastes, composts, crop residues), wastewater, and animal feeds. South Florida uses approximately 50 percent of the phosphorus fertilizer imported into the state of Florida (Reddy et al., 1999). Some of the phosphorus is exported from the drainage basin as agricultural products (i.e., harvested biomass), but a significant amount of the phosphorus applied to the land ends up in upland soils and sedi- ments of ditches and streams, and a portion is then transported by river flow to the lake, where it accumulates in lake sediments (Engstrom et al., 2006) and contributes to eutrophication. The Lake Okeechobee watershed consists of approximately 3.5 million acres, and primary land cover/land uses include: natural areas such as wetlands (37 percent), improved and unimproved pastures (20 and 4 percent, respectively), sugarcane (12 percent), citrus (7 percent), and urban use (11 percent) (SFWMD and FDEP, 2008a). The export of phosphorus to Lake Okeechobee was exacer- bated by the channelization of the Kissimmee River in the 1950s and 1960s and the transport of large volumes of phosphorus-laden sediments. Approximately 10 percent of the phosphorus imported into the Okeechobee basin is eventually exported into the lake, although current estimates are based on limited data sets. The residual mass and annual load from legacy ­phosphorus in the watershed is not currently quantified (Reddy et al., 1996; SWET, Inc., 2008a, 2008b). A total maximum daily load (TMDL) of 140 metric tons (mt) of ­phosphorus per year was established for Lake Okeechobee using a goal of phosphorus con- centration in Lake Okeechobee of 40 ppb (FDEP, 2000). Based on modeling studies, the Florida Department of Environmental Protection (FDEP) selected 40 ppb as a threshold concentration in nearshore waters for preventing imbal- ance in the composition of biotic communities (Havens and Walker, 2002). An estimated 35 mt per year of the load is atmospheric deposition (primarily as dust), leaving a target of 105 mt per year as the waterborne TMDL. Average total water- borne phosphorus loads to Lake Okeechobee in the past 5 years were 630 mt per year—six times greater than the target waterborne TMDL. The recent loads represented a decline from the previous 5-year average of 715 mt, largely due to the drought in 2007 when the total phosphorus load to the lake was 203 mt (Figure 5-5). Over the past 5 years, the average phosphorus concentration in the lake water column has been 179 ppb—4.5 times the target concentration (SFWMD and FDEP, 2008a). Intensive phosphorus-management strategies are  One metric ton equals 2,200 pounds.

Lake Okeechobee 151 1200 Water Year Load Phosphorous Load, Metric Tons per Year Five-Year Average 1000 800 600 400 200 TMDL target: 105 mt/year 0 1980 1984 1988 1992 1996 2000 2004 2008 Year FIGURE 5-5  Annual phosphorus loads into Lake Okeechobee between 1981 and 2007. Figure 5-5.eps SOURCE: Data for 1974–2005 from James et al. (2006); data for 2006–2007 from James and Zhang (2008). needed to reduce loads from the basins and meet the current TMDL of 140 mt of total phosphorus in Lake Okeechobee by 2015. Internal Phosphorus Loads Excessive external phosphorus loads to the lake have accumulated in mud sediments in the center of the lake (Figure 5-6), and they create the current inter- nal phosphorus loads to the lake water column. The phosphorus-rich mud sedi- ment in Lake Okeechobee covers an area greater than 197,684 acres (40 percent of the lake bottom) and has a volume of approximately 162,142 acre-feet. Currently, there are nearly 30,000 mt of phosphorus that have accumulated in the upper 10-cm of these mud sediments (Fisher et al., 2001; see Figure 5-6), representing approximately 60 years’ worth of external phosphorus loads. Phos- phorus accumulated in sediments shows a dramatic increase in loading, begin- ning about 1950, coincident with elemental tracers of phosphate fertilizers (Engstrom et al., 2006).

152 Progress Toward Restoring the Everglades FIGURE 5-6  Lake Okeechobee showing the location of fine mud sediments on the lake Figure 5-6.eps b ­ ottom that can be resuspended by hurricanes and other wind events. bitmap SOURCE: Adapted from Fisher et al. (2001). Internal loads of phosphorus to Lake Okeechobee’s water can be substantial (approximately 200 mt per year) and comparable to external loads (Fisher et al., 2005). These internal loads occur through diffusive flux of phosphorus from sediments to overlying water and during resuspension of surface sediments into the water column during wind events. After three hurricanes (Frances, Jeanne,

Lake Okeechobee 153 and Wilma) moved directly over the lake in 2004 and 2005, sediments became resuspended, and nutrient budgets showed that these sediments became a source of phosphorus to the lake water rather than a sink. Resuspension of sediments also creates turbidity in the lake and prevents light penetration, resulting in poor establishment of SAV. In most hypereutrophic lakes, the bottom sediments are largely derived from deposition of planktonic materials, and the sediments are highly organic in nature. In contrast, one of the sources of Lake Okeechobee’s bottom sediments is clay mineral matter derived from the Kissimmee River basin, and these low-density colloidal materials are easily redispersed following wind- driven mixing events and settle very slowly (Harris et al., 2007), which could have long-term impacts on water quality. The origin and composition of the existing mud sediments and current sedi- ment loads are pertinent to phosphorus management in the lake. At ­ present, s ­ ediments delivered to the lake contain magnesium silicates. These ­colloidal sedi- ments remain suspended in the water column for long periods. This may decrease the longevity of prospective dredging benefits by maintaining ­resuspended sedi- ments in the water column. Also, the concentration of calcium in the water column can affect flocculation of suspended particles. At this time, very little is known about the reactivity of suspended particles with respect to ­phosphorus release and retention and the role of altered water chemistry on sediment resuspension. Implications of Legacy Phosphorus Once the external phosphorus loads from uplands are curtailed through the implementation of best management practices (BMPs) and other phosphorus management strategies in the drainage basin, the critical question concerns how the lake will respond to reduction of the external phosphorus load (Havens et al., 2007). Legacy phosphorus will continue to leach into the water even after other external loads have been reduced, extending the time required for the lake to meet environmental goals (Fisher et al., 2005). Given these conditions, how long will it take for Lake Okeechobee to reach background or alternate stable conditions? For example, in Lake Okeechobee, phosphorus accretion rates have increased about fourfold since the 1900s (from about 0.25 g P/m2/year before 1910 to 0.85 g P/m2/year in the 1980s; Brezonik and Engstrom, 1998), and most of that increase occurred since the 1950s (Engstrom et al., 2006). Although accre- tion of sediment-bound phosphorus suggests that particulate phosphorus flux is downward (i.e., from the water column to sediments), the dissolved reactive (bio- available) phosphorus flux is upward (i.e., from sediments to the water column) in response to concentration gradients established at the sediment-water inter- face (Reddy et al., 2007). Average phosphorus flux from sediments is estimated

154 Progress Toward Restoring the Everglades to be at 0.3 g P/m2/year, which remained approximately constant over a 10-year period (Fisher et al., 2005). At these rates, bottom sediments can be a source of phosphorus for several decades, unless the sediment phosphorus is stabilized through selective management strategies (e.g., chemical amendments). Lake Biota Lake Okeechobee represents an important ecological and recreational resource to the citizens of Florida, and it is an important ecological component of the South Florida ecosystem, both in its own right and as an integral part of the larger system. The lake is home to many species and biotic communities, including some that are (or were) not found elsewhere in South Florida. Some of those species—especially birds—use the lake for part of their life cycles but are important ecosystem components elsewhere at other times. The changes in Lake Okeechobee water quantity and quality, however, are threatening the condition of native lake biota, including vegetation fishes, and birds and exacerbating the spread of exotic species. Vegetation The plant communities of Lake Okeechobee are both the linchpin of the aquatic ecosystem and a sensitive indicator of the status of water quantity and quality in the lake. Historically, a series of plant communities occurred roughly in bands around the lake, with a distribution closely correlated with hydroperiod (Havens and Gawlick, 2005), although the littoral zone before the lake was diked is not as well documented. The size, community composition, and geographic arrangement of these communities have been strongly affected by the Herbert Hoover Dike and by water level fluctuations in the lake. Some bands have been entirely lost (e.g., pond apples) (James and Zhang, 2008), and exotic species that are highly tolerant of changes in water level have invaded and spread, altering the dynamic responsiveness of the vegetation to water changes. SAV is a keystone indicator of many aspects of lake functioning. SAV sta- bilizes bottom sediments, provides essential habitat for fish and wildlife, and serves as a substrate for the periphyton community that removes nutrients from the water column (Havens and Gawlick, 2005; Havens et al., 2005; RECOVER, 2007a). SAV biomass and cover was markedly decreased after Hurricane Wilma, from approximately 54,000 acres in late summer 2004 (SFWMD and FDEP, 2005) to nearly 11,000 acres in August 2005 and less than 3,000 acres in 2006 (SFWMD and FDEP, 2008a). SAV biomass is highly sensitive to light penetration (Havens, 2003) and was affected by the high turbidity of the water, plus distur-

Lake Okeechobee 155 bance from wind action and high water levels, although it started to recover in 2007. Recovery requires high light penetration, which in turn results from low lake stages or lack of suspended solids or low concentrations of phytoplankton. However, the goal for shoreline water clarity (100 percent visibility to the lake bed from May through September) was met less than 10 percent of the time during the past 5 years (SFWMD and FDEP, 2008a). The effects of sediment and water quality (especially phosphorus) on both the total amount and the species composition of the SAV are less well understood and warrant inclusion in the research agenda. A band of floating and emergent vegetation constitutes the littoral zone, which occupies approximately 98,842 acres along the western perimeter of the lake (Figure 5-1). This zone is characterized by high species diversity and a complex pattern of community occurrence, responding to small differences in water depth and hydroperiod. The littoral zone provides essential habitat for fish, wading birds, and other animals for nesting and feeding, and functions like the SAV zone as a keystone community to structure lake food webs and to affect water quality through uptake and stabilization or remobilization of P-rich bottom sediments (Havens and Gawlick, 2005; Johnson et al., 2007). The littoral zone has undergone dynamic change over the past three decades, largely in response to changes in hydroperiods due to variations in lake level (Havens and Gawlick, 2005). Very low lake stages in the past permitted the invasion and spread of two damaging exotic species (Melaleuca and Panicum repens [torpedograss]); the former species required an expensive and long removal program that has been successful. High lake stages reduced native bulrush stands and have enhanced the distribution of floating-leaved exotic species (Eichhornia, water hyacinth, and Pistia, water lettuce). A recent extensive review of the response of both vegetation and fauna to lake levels (Johnson et al., 2007) clearly established two findings: first, most if not all native plant species are highly sensitive to small changes in stage and hydroperiod; second, an optimal range of water level fluctuations promotes a healthy vegetation mosaic that in turn supports a diverse and productive animal community. This review suggests that under the projected management of Lake Okeechobee in accord with Comprehensive Everglades Restoration Plan (CERP) planning, maintenance of lake levels between 12.1 and 15.1 feet above mean sea level should support extensive, dense, and diverse stands of SAV and fluctuating conditions in the interior littoral zone, with positive effects at least on largemouth bass and probably other fish species. However, hurricanes, droughts, and other considerations will influence the maintenance of the lake at those levels. Even with optimal lake levels, exotic species management is crucial to rehabilitating the Lake Okeechobee ecosystem. More than 80 species of non-

156 Progress Toward Restoring the Everglades indigenous plants are found in the Lake Okeechobee region, of which 10 are considered important pests (James and Zhang, 2008). The South Florida Water Management District (SFWMD) implements an extensive monitoring and control effort for exotic plant species. Fishes, Birds, and Exotic Animals The changes in water quantity and quality—especially lake level and t ­urbidity—and the related changes in vegetation have had substantial effects on the fishes and birds of the lake. In recent years, in part due to the four hurricanes that affected the lake in 2004 and 2005, piscivorous fishes declined, while omnivores and planktivores increased. There were marked declines in the fish species of greatest recreational and commercial interest, particularly largemouth bass (Micropterus salmoides) and various species of sunfish (Lepomis). Lake Okeechobee was historically an important area for wading birds to nest and feed. White ibis (Eudocimus albus), great egret (Ardea albus), snowy egret (Egretta thula), glossy ibis (Plegadis falcinellus), and great blue heron (Ardea herodias) were the bulk of the species that historically used the lake (David, 1994a), but tricolored herons (Egretta tricolor) and little blue herons (Egretta caerulea) also occurred. Before the 1940s, most of these species were considered so numerous that counts were not made. Numbers of wading birds appeared to peak in the early and mid-1970s due to a large increase in the number of white ibis, when 10,000-plus pairs nested. Increased lake levels that occurred after a change in the lake regulation schedule in 1978 seem to be related to the decline in wad- ing bird numbers on the lake since the late 1970s (David, 1994b). Today Lake Okeechobee is still an important nesting area for wading birds, but the number of birds varies greatly from year to year. Nesting effort of wading birds has been greatest during moderate lake stages (between 13.6 and 15.5 feet for the mean January stage) and is typically very low during years with high or low lake stages (David, 1994b; Marx and Gawlik, 2007). Moderate lake stages probably increase productivity of fish and maximize the potential foraging habitat for wading birds (Smith et al., 1995). Although nesting effort in 2005 was below average, nesting effort in 2006 was near the historic high of 1974, with more than 10,000 nests on the lake (Marx and Gawlik, 2007). However, in the drought year of 2007 only 550 nests were found on the lake—the third lowest count on record (Marx and Gawlik, 2007). Until recently, Lake Okeechobee had been one of the two most important areas for nesting of the endangered snail kite (Rostrahamus sociabilis) in Florida,

Lake Okeechobee 157 along with Water Conservation Area (WCA) 3A. Kites nested frequently on the lake in the 1970s and 1980s (Snyder et al., 1989), peaking from 1991–1993 with 63–132 nests annually (Rodgers, 2007). Despite reaching a peak population size of more than 3,100 individuals, no kite nests were found on the lake from 1999 through 2002, and since then few nests have been initiated there (USFWS, 2007). When kites did nest on Lake Okeechobee, water levels directly affected the success of their nests. Kites on Lake Okeechobee from 1997–2007 produced an average of only about 3 young annually. This value is much lower than the mean of 87 young fledged per year in WCA-3A and 19 young fledged per year in the Kissimmee Chain of Lakes region (Martin et al., 2007b). The factors responsible for reduced use of Lake Okeechobee by kites are not fully understood, as no quantitative analysis of causes has been conducted. However, reduced use appears to be associated with declines in kite foraging habitat from prolonged periods of both high and low water levels that have affected apple snail (Pomacea paludusa) populations (USFWS, 2007), which appear to be low and declining (Darby et al., 2006; Darby, 2007). The pro- portion of kite nests successfully producing young on Lake Okeechobee was positively related to stage levels, with low water levels having a more adverse effect on kites than other water levels (Beissinger and Snyder, 2002; Rodgers, 2007; Snyder et al., 1989). In excess of 100 species of nonnative animals are found in and around the lake (James and Zhang, 2008), including channeled or island apple snails (­Pomacea insularum), oscar (Astronotus ocellatus), sailfin catfish (­Pterygoplichthys multiradiatus), and Cuban tree frogs (Osteopilus septentrionalis) (Ferriter et al., 2008). Although only a few of the many exotic fish species found in Lake Okeechobee have become established, and although they do not appear to have had large effects on the fisheries in the lake (D. Fox, Florida Fish and Wildlife Conservation Commission, personal communication, 2007), there is not enough information for this committee to evaluate the effects of exotic animals on Lake Okeechobee. Ferriter et al. (2008) conclude that although exotic animals could become, or might already be, problematic, “not enough is known about the population dynamics, reproduction, feeding habits and biology of any of these nonindigenous animal species to make evaluations of their current or future potential impacts to the Lake Okeechobee region.” Given the experiences with exotic animals elsewhere, it would appear that the general matter of exotic animals deserves serious attention. Despite the existence of several efforts to monitor and manage specific exotic animal species, there is no coordinated effort to track the wide range of exotic animals in Lake Okeechobee or the South Florida ecosystem as a whole.

158 Progress Toward Restoring the Everglades State Changes As ecosystems are altered, they frequently undergo what is termed a regime shift, in which their physical characteristics, biogeochemistry, and biology change dramatically (Folke et al., 2004). Once a shift has occurred to a new alternative stable state, the new ecosystem regime may resist recovery, despite intensive restoration efforts (see also Chapter 2). Such state changes are par- ticularly well known for lakes that shift from a clear-water regime—in which phosphorus inputs, phytoplankton biomass, and recycling of phosphorus from sediments are relatively low—to a turbid-water regime—in which these same variables are relatively high (Carpenter, 2003; Scheffer and van Ness, 2004). Under the enriched, turbid-water regime, submerged plants are reduced or eliminated and primary production is dominated by phytoplankton. Increases in bottom-feeding fishes destabilize the sediment substrate, further making it more susceptible to resuspension by winds and thereby increasing turbidity. Sediment resuspension not only decreases light penetration but also recycles phosphorus back into the water column. Anoxic conditions at the bottom can also release phosphorus from sediments (Fisher et al., 2005). Turbid phosphorus- rich conditions favor dominance by cyanobacteria, which tend to persist even when external nutrient loads are reduced. The conditions are even influenced by the trophic structure of the animal community, with increased fish popula- tions consuming zooplankton that would keep the phytoplankton abundance in check and destabilizing vegetation beds. Current conditions in Lake Okeechobee correspond closely to the conditions generally described for regime shifts in lake ecosystems, making the general properties described in the literature of great relevance to the management of this lake. The nexus of interrelationships involved in regime shifts in lakes complicates restoration efforts, including the reduction of phosphorus inputs (Carpenter, 2003; Søndergaard et al., 2007). The lakes may remain turbid and susceptible to algal blooms as a result of the remobilization of phosphorus in sediments due to anoxia or resuspension or because of low rates of grazing of phytoplankton. Controlling populations of planktivorous fishes that reduce zooplankton grazing or benthic fishes that cause sediment resuspension—either by removing them or by introducing larger fish to prey on them—has been used to assist recovery in some lakes. Drawing down water levels to remove sediments or to promote vascular plant growth also has been used, as is illustrated by a short-term experimental drawdown of the lake in 2000 (Steinman et al., 2002b). For most temperate lakes that have been studied, cessation of excessive phosphorus inputs has resulted in recovery over 10 to 15 years (Søndergaard et al., 2007), although the presence or absence of key plants and animals that affect water clarity may

Lake Okeechobee 159 have an impact on recovery (Ibelings et al., 2007). Indeed, enough is known about physical and chemical changes that have occurred in Lake Okeechobee and their effects on its biota to indicate that any return to the pre-drainage state will not be quick or easy. EFFECTS OF THE LAKE’S CONDITION ON THE SOUTH FLORIDA ECOSYSTEM The construction of levees, canals, and other water control structures has significantly altered Lake Okeechobee and its interactions with the South Florida ecosystem. The Herbert Hoover Dike interrupted the southward flow of water, and the water quality difficulties described above pose considerable constraints to the movement of water from Lake Okeechobee to the southern part of the eco- system in its current condition. As a result, excess water from Lake Okeechobee currently is released through constructed connections to the Caloosahatchee and St. Lucie estuaries, the lower east coast, and the WCAs. Changing Flows to the Estuaries The Caloosahatchee Estuary to the west and the St. Lucie Estuary and Lake Worth lagoon to the east (Figure 5-2) have been extensively altered by inlet opening, channelization, and wetland drainage. Most significantly, they have been greatly affected by canal drainage from Lake Okeechobee. Through the CERP, this latter effect is to be mitigated by reducing and modulating freshwater inflows to avoid ecologically harmful low and high flows. The Caloosahatchee Estuary receives most of its freshwater inflow from the historically meandering Caloosahatchee River, which was supplied by rainfall in its watershed. Beginning in the 1890s, the river was channelized and con- nected to Lake Okeechobee to promote both navigation and drainage from the lake. An extensive network of canals was constructed to drain agricultural lands in the watershed, and the tidally influenced portion of the estuary was reduced by operation of the S-79 control structure. Approximately 55 percent of the regulatory (flood control) discharge from Lake Okeechobee is sent down the Caloosahatchee River (J. Obeysekera, SFMWD, personal communication, 2008), where it often dominates the wet-weather discharge to the estuary (Figure 5-7). Together, this discharge and the altered drainage patterns within the watershed have greatly changed the pattern, quantity, and timing of freshwater inputs, have caused abnormal salinity fluctuations, and have increased loading of nutrients and other materials (Doering and Chamberlain, 1999). The St. Lucie Estuary was originally a freshwater system with intrusions of salt water during occasional opening of the ocean inlet. It became an estuary

160 Progress Toward Restoring the Everglades 25000 Discharge from Watershed Discharge from Lake 20000 Flow (cubic feet per second) Data are provisional and subject to change 15000 10000 5000 0 1/1/04 1/1/05 1/1/06 1/1/07 1/1/08 FIGURE 5-7  Total discharge rate into the Caloosahatchee Estuary (watershed releases) at S-79. The portion of the discharge rate accounted for by Lake Okeechobee releases is shown in blue and the portion from the C-43 basin is5-7.eps yellow. Figure shown in SOURCE: P. Doering, SFWMD, personal communication (2008). when the permanent inlet was artificially established in 1898. Its watershed was expanded by agricultural and urban development and drainage; it was connected to Lake Okeechobee by the C-44 canal to provide for navigation and regulatory releases. It receives 21 percent of Lake Okeechobee’s regulatory (flood control) discharge (J. Obeysekera, SFMWD, personal communication, 2008), and like the Caloosahatchee, the freshwater inflows are excessive at times and insufficient at others (Chamberlain and Hayward, 1996; Doering, 1996; Figure 5-8). Thick muddy deposits cover large areas of the bottom of the estuary, making it unsuitable for aquatic vegetation and other benthic life (Doering, 2007). Lake Worth Lagoon was historically a freshwater lake, but the creation of permanent inlets has made it estuarine. Lake Okeechobee discharges from drain- age canals toward the lower east coast result in occasional excessive releases of fresh water into the estuary.

Lake Okeechobee 161 7000 Discharge from Watershed Discharge from Lake 6000 Data provisional and subject to change Flow (cubic feet per second) 5000 4000 3000 2000 1000 0 1/1/04 1/1/05 1/1/06 1/1/07 1/1/08 FIGURE 5-8  Total discharge to the St. Lucie Estuary from C-44 during Water Year 2006. The Figure 5-8.eps portion of the discharge accounted for by Lake Okeechobee releases is shown in blue and the portion from the St. Lucie river basin is shown in yellow. SOURCE: P. Doering, SFWMD, personal communication (2008). These hydrologic changes, particularly as a result of drainage from Lake Okeechobee and the northern Everglades, have resulted in large ecological changes and a reduction in productivity of living resources. These changes are generally caused by exaggerated variations in salinity within the ­estuaries. How- ever, changes in estuarine circulation and density stratification, and increased loading by nutrients (including not only phosphorus, which receives most atten- tion in Lake Okeechobee and the Everglades, but also nitrogen, which con- tributes to the eutrophication of estuarine environments), sediments, and toxic contaminants are also factors. As a consequence, in addition to salinity stress, estuarine organisms have to contend with low-oxygen conditions, harmful algal blooms (red tides and blue green algae), decreased light availability, toxins, and siltation (Abbott et al., 2007). The deterioration of these ecosystems is especially evident in the loss of o ­ yster reefs and beds of SAV, both of which provide important and productive

162 Progress Toward Restoring the Everglades habitats. Oysters have been particularly affected by stressful or lethal incursions of low-salinity and heavy siltation (Wilson et al., 2005). Marine vascular plants such as turtle grass (Thalassia testudinum) may be reduced or extirpated dur- ing low-salinity episodes, while freshwater vascular plants such as tape grass (­Vallisneria americana) are stressed by high-salinity incursions up the Caloosa- hatchee ­Estuary (Doering et al., 1999; Doering and Chamberlain, 2000; ­Kraemer et al., 1999). For these reasons, increasing areal coverage of both oysters and SAV is an important restoration goal for the northern estuaries (Doering et al., 2002). Water Quality Impacts South of Lake Okeechobee The flora and fauna of the unimpacted areas of the southern part of the Everglades ecosystem are severely phosphorus-limited, and they are adapted to nutrient-poor conditions. As a result, any small addition of nutrients, especially phosphorus, can have a dramatic effect on the structure and productivity of this ecosystem (Childers et al., 2001; Gaiser at al., 2005). At present, the nutrient-rich waters of Lake Okeechobee have minimal effects on the Everglades Protection Area because only 4 percent of the lake’s outflow (on average) goes to the WCAs (see Box 5-1). Nutrients discharged from the Everglades Agricultural Area (EAA) and C-139 basins have been identified as the major sources impacting the downstream Everglades Protection Area. Source control strategies such as BMPs and STAs have been used to reduce phosphorus loads from these basins to the Everglades Protection Area (Adorisio et al., 2007). Among the most prominent and widely documented effects of introducing water with high phosphorus concentrations into the greater Everglades region is the spread of cattails (Typha spp.) at the expense of sawgrass and other species typical of Everglades communities (Chiang et al., 2000; Craft et al., 1995; Noe et al., 2001; NRC, 2005; Scheidt and Kalla, 2007). Thus, sending water to the south that has high concentrations of phosphorus risks perturbing the vegetation community even further beyond its current disturbed state, which likely will affect other aspects of the biological community, including vertebrates. To address these concerns, the state adopted a phosphorus criterion of 10 ppb (see Box 5-2) that is to be met during the first phase of its “Long Term Plan” (2003–2016). The phosphorus criterion is one part of a phosphorus stan- dard, which also includes moderating provisions. These moderating provisions allow the use of best available phosphorus reduction technologies as a substitute for achieving the actual criterion. The assessment of compliance with the phos- phorus ­criterion is based on a geometric mean from a network of monitoring

Lake Okeechobee 163 BOX 5-2 Judicial and Legislative Context for Lake Okeechobee Restoration Efforts Water quality in Lake Okeechobee and the larger Everglades system has been a matter of considerable legislative, judicial, and administrative action since the 1980s. Rizzardi (2001) provides considerable insight into the complex legal issues that have accompanied those efforts. Litigation began in 1988 when the U.S. Attorney sued the SFWMD and the Florida Department of Environmental Regulation (DER) (now the De- partment of Environmental Protection [DEP]), alleging that those agencies were violat- ing the state’s water quality standards for phosphorus in the Everglades National Park (ENP) and the Loxahatchee National Wildlife Refuge (LNWR).a With the intervention of Governor Lawton Chiles in July 1991, the SFWMD, Florida DER, and U.S. Depart- ment of Justice entered into a settlement agreement that was subsequently adopted by the court as a consent decree.b The consent decree stipulated that state water quality standards would be met in ENP and LNWR by July 2002. The agreement also called for construction of a series of STAs and regulations requiring agricultural enterprises in the Everglades Agricultural Area (EAA) to implement best management practices BMPs. The SFWMD initiated its surface water improvement and management (SWIM) planning process in 1991 to implement terms of the consent decree, and the Florida legislature passed the Everglades Protection Act to provide a statutory framework. When the SFWMD issued the SWIM plan in March 1992, it was subjected to numerous challenges under Florida’s Administrative Procedure Act.c The legislature again stepped in and passed the Everglades Forever Act in 1994 (Ch. 373.4592, F.S.), which largely superseded the Everglades Protection Act and did the following (Rizzardi, 2001): • in addition to the previously covered federal areas (ENP and LNWR), it extended jurisdiction to the entire Everglades; • it changed time schedules for compliance from 2002 to 2006; • it authorized the Everglades Construction Project that included six storm-water treatment areas (STAs); • it authorized the use of ad valorem taxes to provide funding for those projects; • it required rulemaking to establish a numeric criterion for phosphorus concentra- tions; and • it authorized acquisition of agricultural lands. Based on information gained from an enormous research effort, a phosphorus crite- rion of 10 ppb was established. During the 2006 Florida legislative session, moderating provisions were added to the Everglades Forever Act that effectively extended the water quality compliance deadline until 2016, at the earliest. Special attention was given to water quality in Lake Okeechobee with passage of the Lake Okeechobee Protection Act (LOPA) by the Florida legislature in 2000. That legislation establishes authority for a comprehensive watershed program to reduce continued

164 Progress Toward Restoring the Everglades BOX 5-2 Continued phosphorus loads to the lake based on a TMDL for total phosphorus (TP) developed by the Florida DEP. The legislation requires that the TMDL of 140 metric tons TP per year be met by 2015. The 2004 Lake Okeechobee Protection Plan (LOPP) developed under the act provided a phased, comprehensive approach to reduce TP loading to Lake Okeechobee. Efforts to clean up the lake were given an additional boost by the accelerate restoration of America’s Everglades (Acceler8 program) and the Lake Okeechobee and Estuary Recovery (LOER) Plan initiated by the state in 2004 and 2005, which fast-tracked numerous CERP construction projects that affect the lake and the northern estuaries (e.g., C-43 and C-44 reservoirs; STAs north of the lake; Lake Okeechobee Watershed project). The LOPA was further expanded in 2007 with p ­ assage of the Northern Everglades and Estuaries Protection Program (described in more detail later in this chapter). a U.S. v. South Florida Water Management District, Case No. 88-1886 CIV-HOEVEL- ER (S.D. Fla.). b U.S. v. South Florida Water Management District, 847 F. Supp. 1567 (S.D. Fla. 1992). c Sugar Cane Growers Cooperative of Florida; Roth Farms, Inc.; and Wedgworth Farms, Inc. v. SFWMD, DOAH Case No. 92-3038 (petition filed 4/9/92); Florida Sugar Cane League, Inc.; U.S. Sugar Corporation; and New Hope South, Inc. v. SFWMD, DOAH Case No. 92-3039 (petition filed 4/27/92); Florida Fruit and Vegetable Assn.; Lewis Pope Farms; W.E. Schlechter & Sons, Inc.; and Hundley Farms, Inc. v. SFWMD, DOAH Case No. 92-3040 (petition filed 4/9/92). stations established for this purpose within the Everglades Protection Area (see Box 1-1; SFWMD and FDEP, 2006, Appendix 2C-1). There are four components of the total phosphorus criterion for the Everglades, passed by the Florida legis- lature in 2003 and approved by the Environmental Protection Agency in 2005. All monitoring sites must: • have a geometric mean of total phosphorus concentrations of less than or equal to 10 ppb in 3 of 5 years, • have annual total phosphorus concentrations of less than or equal to 11 ppb across all stations, • have total phosphorus concentrations less than or equal to 15 ppb ­annually at all monitoring stations, and • have a five-year geometric mean of total phosphorus concentrations aver- aged across the network of less than or equal to 10 ppb.

Lake Okeechobee 165 Not later than December 31, 2008, the FDEP will evaluate the first 5 years of monitoring data and approve any incremental phosphorus reduction measures that are needed (373.4592(4)(e), F.S). STEPS TOWARD REHABILITATION OF LAKE OKEECHOBEE AND AFFECTED DOWNSTREAM ECOSYSTEMS Earlier sections of this chapter have described water quantity and quality problems in Lake Okeechobee and its watershed, as well as the effects of these problems on the lake biota and downstream ecosystems. The major challenges related to restoration of Lake Okeechobee are (1) excessive phosphorus loads, (2) large amounts of phosphorus stored in the lake sediments, (3) abnormally high and low water levels, and (4) rapid spread of exotic and nuisance plants. Improv- ing water quality and the hydrologic regimes in and around Lake Okeechobee is critical to the long-term success of the Everglades restoration and to improving the condition of the northern estuaries. Thus, the committee agrees with this important premise of the CERP. Improving Water Quality Three major components need to be considered in water quality rehabili- tation efforts: (1) water quality in Lake Okeechobee, with special attention to management of the large mass of phosphorus in the sediment; (2) phosphorus management in the Lake Okeechobee basin; and (3) effectiveness of the storm- water treatment to the south. The key questions that need to be addressed are: (1) Will Lake Okeechobee respond to phosphorus load reduction? (2) If so, how long will it take for the lake to recover and reach its background condition? (3) Are there any economically feasible management options to hasten the recovery process? Release of the internal load (a consequence of past excessive external loads) can extend the time required for the lake to reach its original condition. This lag time for recovery should be considered in developing man- agement strategies for the lake. Existing, planned, and potential activities and their potential restoration benefits are discussed below. Options for Managing Loads Internal to Lake Okeechobee Several methods for managing sediment can address internal loading of con- taminants; the most common ones include chemical treatment, oxidation, and dredging (Cooke et al., 1993). A feasibility study of alternatives was conducted to evaluate improvements in water quality by managing phosphorus released from

166 Progress Toward Restoring the Everglades sediment within the lake (SFWMD, 2003). The study considered approximately 30 possible actions, and ultimately, three options were evaluated in detail with respect to cost, effectiveness, and timeliness: (1) hydraulic dredging; (2) in-place chemical precipitation with aluminum compounds; and (3) no in-lake action. Removal of mud sediments from Lake Okeechobee via dredging will require an order of magnitude greater effort than other lake restoration projects (Cooke et al., 1993). Removing 12 inches of sediments from the lake would take out approximately 94 years’ worth of phosphorus accumulation. However, dredging of surface sediments alone will not reverse eutrophication unless external loads are also curtailed (Kleeberg and Kohl, 1999). Hydraulic dredging of deposits in the open lake was estimated to take over 15 years to accomplish and to cost roughly $3 billion in 2002 dollars, although costs would vary with water level and depth of dredging. Despite these high costs, the dredging would leave behind a significant amount of phosphorus-enriched sediment, which would continue to release phosphorus into the water column for several decades. Several post-dredge sediment management options were identified, including beneficial reuse. However, the benefits of widespread dredging activities were not deemed to be cost-effective (SFWMD, 2003). Nevertheless, during the drought of 2006–2007, the SFWMD removed approximately 1,300 acre-feet (or 1.6 million cubic meters) of mud sediments along exposed shorelines in Lake Okeechobee (SFWMD and FDEP, 2008a). This large volume represents less than 1 percent of the 162,142 acre-feet of mud sediments estimated in the lake (Engstrom et al., 2006). Chemical applications are intended to bind phosphorus; they usually include aluminum (alum), calcium (lime), or iron (ferric chloride; Cooke et al., 1993). In-lake treatments to control phosphorus concentrations have been used suc- cessfully elsewhere on a smaller scale (Cooke et al., 1993; Welch and Cooke, 1999). The SFWMD (2003) considered in-lake treatment using aluminum sulfate (“alum”) and sodium aluminate to reduce dissolved and suspended phosphorus concentrations. Aluminum compounds could be particularly effective due to their dual mode of action for phosphorus removal. Concern has been expressed that application of aluminum sulfate compounds could have the unintended consequence of adding sulfate, which is linked to mercury methylation, to the ecosystem. The SFWMD predicted that aluminum compounds could inactivate existing phosphorus and much of the new phosphorus added to sediments for approximately 15 years at a cost of $500 million in 2002 dollars. However, unless additional source controls are implemented to reduce phosphorus loads to the lake, the lake would progressively return to the original contaminated state, because the surface of aluminum oxy-hydroxides would become fouled and buried with sediments over time.

Lake Okeechobee 167 These actions were contrasted against a “no in-lake action” alternative, in which external source reductions would be emphasized. If the TMDL could be met by 2015, the algal bloom frequency would be reduced by 25 percent to less than 15 percent by 2015 and to below 10 percent by 2028. SFWMD (2003) estimated that the lake would reach a steady state in approximately 35 years with inflow at 140 mt of phosphorus per year. Based on this analysis, the SFWMD selected the no in-lake action alternative as the preferred option (SFWMD and FDEP, 2007). The committee does not challenge the scientific basis for the decision to place priority on reducing phosphorus in the watershed over in-lake treatment. Nonetheless, the choice of the “no-action” alternative for in-lake treatment makes achievement of the target of 40 ppb concentration by 2015 very unlikely. Without in-lake treatment to substantially control resuspension of the sediment load, water-column concentrations are likely to remain in excess of the target for several decades. That reality may make achieving water objectives downstream of the lake much more difficult. Managing External Phosphorus Loads As noted in Box 5-2, over the past several decades a variety of federal and state agricultural programs have been used to reduce the flow of phosphorus from watersheds that empty into Lake Okeechobee. One of the most important was the Lake Okeechobee Protection Act (LOPA), enacted by the Florida legisla- ture in 2000, which mandated preparation of a comprehensive plan to meet the TMDL of 140 mt per year of total phosphorus by 2015. The plan, known as the Lake Okeechobee Protection Plan (LOPP), published in 2004, relied on several on-going projects, expansion of cost-share programs to all agricultural activities, regional structural measures, and CERP reservoirs, STAs, wetlands restoration, and removal of phosphorus-rich sediment from tributaries. More recently, the Northern Everglades and Estuaries Protection Program was established by action of the state of Florida in 2007 to strengthen protec- tion of the Northern Everglades, including the estuaries, and to expand the use of the state’s Save Our Everglades Trust Fund for use toward restoration of the Northern Everglades. In February 2008, the SFWMD released the Lake Okeechobee Watershed Construction Project: Phase II Technical Plan (LOWCP- II), a comprehensive plan to implement the Northern Everglades and Estuaries Protection Program (Box 5-3; SFWMD et al., 2008). The new plan expanded LOPP, with objectives to:

168 Progress Toward Restoring the Everglades BOX 5-3 Assessment of the Lake Okeechobee Watershed Construction Project: Phase II Technical Plan (LOWCP-II) Overall, the LOWCP II Technical Plan is a very useful document. It provides good background on earlier actions to improve water quality and ecological conditions of the Kissimmee River–Lake Okeechobee watershed. It also provides an extensive list and assessment of management measures relative to their state of design, likelihood of implementation, state of information about benefits, and costs. In addition, the plan includes an evaluation of four alternatives for management. Those who developed the plan should be applauded for assigning uncertainty levels (1–5) to the management measures (see Table 5-1). By assigning those levels, realistic expectations and chal- lenges are presented. In doing so, weaknesses of the plan are also revealed. Many of the management measures are assigned Levels 3–5, meaning they are not more than a concept with considerable uncertainty about their benefits and costs and whether they will be implemented. In that sense, they share many of the same uncertainties as elements of the CERP. Although the technical plan for the Northern Everglades is very good, there are s ­ everal noteworthy issues. First, there may be an undue confidence placed on Level 1 and Level 2 BMPs regarding both the extent to which practices are likely to be imple­ mented and their initial and continuing effectiveness. In general, BMPs include a number of practices that are neither intensively managed nor routinely inspected and frequently monitored. The Florida Ranchlands Environmental Services Project is an exception to the more general case of BMPs, but this program currently involves only 8,500 acre-feet of storage and just under 2,000 metric tons of phosphorus (SFWMD et al., 2008, pp. 9–11). Second, it would have been helpful to provide a listing in Chapter 9 of which manage- ment measures are included in the preferred plan along with their specific ­ expected reductions in phosphorus and the uncertainty levels to which they were ­assigned. Only some of that information can be gleaned from the details of Table 7-9 and Table 8-2 in the technical plan. Estimated reductions are given only by the four alternatives and groups of management measures within the alternatives. Third, cost estimates are not associated with particular management measures. Without that relationship, readers are not able to judge for themselves the relative cost-effectiveness of the various measures. It is also not clear from the document as to whether streams of revenues coming from various sources identified in the plan will be sufficient to cover anticipated costs. Despite these issues, the committee commends the state on its Northern Everglades initiative. The state is making appropriate investments in improving water quality by initially focus- ing on source control in the Lake Okeechobee watersheds.

Lake Okeechobee 169 • Reduce phosphorus loads to meet the TMDL of 140 mt/yr for the lake; • Manage lake levels to keep them within ecologically desirable ranges; • Manage releases from the lake to achieve salinity-related flow targets for the St. Lucie and the Caloosahatchee estuaries; • Identify opportunities for alternative water supply sources in the water- shed; and • Maintain water supply capability for the Lake Okeechobee Service Area. All watersheds that flow toward the lake are covered by the plan. LOWCP-II lists and briefly discusses approximately 120 management mea- sures that contribute to storage capacity and/or phosphorus load reduction (the water storage components are discussed in more detail later in this chapter). Each management measure is assigned to one of five levels based on confidence and certainty in its costs and benefits. The criteria (listed in Table 5-1) range from Level 1 projects—with well-established configuration, certain implementation, high benefits, and reliable cost estimates—to Level 5—with many uncertainties about their configuration, likelihood of implementation, benefits, and costs. The alternative identified as the “preferred plan” (see Table 5-2) was consid- ered to be the most-efficient and most-effective combination of water storage capacity and phosphorus load reduction. Nevertheless, only 68 percent of the p ­ hosphorus load reduction in the plan was attributable to Level 1 and Level 2 management measures. Measures with moderate to low levels of implementation and projected benefits certainty (Levels 3 and 4) represented 15 and 14 percent, respectively, of the total planned phosphorus load reduction. Cost estimates for the first phase of implementation are $260–320 million for non-CERP projects and $1–1.4 billion for CERP projects (SFWMD et al., 2008). Given the current state budget and the recent allocation of only $50 million in state funds to all Everglades-related restoration efforts in 2009, progress could be much slower than had been originally anticipated when the project was launched with an anticipated Northern Everglades restoration budget of $100 million per year (complementing the $100 million per year pledged to CERP/Acceler8). Water-Quality Treatment Downstream of Lake Okeechobee Consideration of several factors leads the committee to conclude that there is a significant likelihood that the TMDL will not be achieved by 2015. First, SFWMD et al. (2008) estimate that the average annual loading of phosphorus on the lake is  514 mt per year. Considering an estimated 35 mt per year of the load is atmospheric deposition, the plan evaluates project alternatives against a target of 105 mt per year as the waterborne TMDL, or a reduction of 409 mt/yr.

170 Progress Toward Restoring the Everglades TABLE 5-1  Levels Used to Classify the State of Maturity of Management Measures Management Configuration Implementation Projected Benefits Cost Estimate Measure Level Information Certainty Certainty Confidence 1 Well Established Certain Very High Very High 2 Known High High High 3 Conceptual Moderate Moderate Moderate 4 Limited Low Low Low 5 Very Limited Uncertain Very Low Very Low SOURCE: SFWMD et al. (2008). TABLE 5-2  Preferred Plan Features Management Measure Levela Local Project Features Lake Okeechobee Watershed Phosphorus Source Control Programs SFWMD Phosphorus Control Programs 1&2 FDACS Agricultural BMP Programs Supplemental Nonagricultural BMP Programs Land Management Programs Comprehensive Planning/Land Development Regulations 3 Farm and Ranchland Protection Program Partnership 4 Florida Ranchlands Environmental Services Project 2 Alternative Water Storage Facilities 1, 3, & 4 Local Initiatives 1 Regional Features Storage 4 Stormwater Treatment Areas 1–5 Reservoir Assisted Stormwater Treatment Areas 4 Aquifer Storage and Recovery (contingent on findings from test well) Deep Injection Wells 4 Other Projects In-Lake Treatment 4 Innovative Nutrient Control Technologies 1,4, & 5 Wetland Restoration 3 Miscellaneous Projects 3&5 a See Table 5-1 for definition of management measures. SOURCE: Information from SFWMD et al. (2008). �������

Lake Okeechobee 171 current trends on the loading of phosphorus to Lake Okeechobee (as shown in Figure 5-5) are upward, not downward. Second, a high degree of uncertainty about performance and financing is associated with many elements of the LOWCP-II. Third, implications of choosing the “no-action” option for in-lake treatment were discussed in the preceding section of this report. Failure to achieve or even approach the 40 ppb target in the lake may have serious consequences to current plans for restoring elements of the Everglades system downstream of Lake Okeechobee. STAs are constructed wetlands used as buffers to retain nutrients and other contaminants. Most of the phosphorus in STAs is stored in soils and sediments via surface adsorption on minerals, precipitation, and immobiliza- tion in the cellular tissue of plants and microbes, which may ultimately be buried with refractory organic compounds. Wetland soils tend to accumulate organic matter due to suppressed rates of decomposition. Soil accretion rates for constructed wetlands can range between a few millimeters to more than one centimeter per year. Accretion rates in productive natural wetland systems such as the Everglades have been reported as high as one centimeter or more per year. The genesis of this new material is a relatively slow process, which may affect the nutrient retention characteristics of the wetland. With time, productive wetland systems will accrete organic matter (which ultimately forms peat) that has different physical and biological characteristics than the underlying soil. STAs are usually managed to improve their overall performance and to maintain expected water quality. For example, small-scale wetlands can be managed effectively by altering hydraulic loading rates or integrating them with conventional treatment systems, while large-scale systems can be managed by controlling nutrient/contaminant loads. Management of newly accreted material by consolidation, hydrologic manipulation (water level drawdown), application of soil amendments and/or soil removal can improve the overall longevity of STAs to maintain water quality. The first STA became operational in 1994 when just 3,800 acres of cells 1–4 of STA-1W were brought online (Figures 5-9 and 5-10). In 2007 the total effective area of STAs was 34,276 acres. Addition of new units made possible a rapid increase in the volume of stormwater that could be treated, increasing from 183,000 acre-feet in 1996 to 1.44 MAF in 2006. The drought of 2007 caused a dramatic drop in the volume of water treated (SFWMD and FDEP, 2008a). The effective treatment area of an STA refers to the wetted or flooded area of the project where  the vegetation grows, which water flows over; it does not include the levees, structures, etc. It is usually around 85 or 90 percent of the total project area (T. Piccone, SWFMD, personal commu- nication, 2008).

172 Progress Toward Restoring the Everglades FIGURE 5-9  Location of stormwater treatment areas.5-9.eps Figure bitmap SOURCE: Pietro et al. (2008). Performance of the STAs is measured primarily by two indicators: how effi- ciently they reduce the concentration of phosphorus in the inflow, and the total mass of phosphorus removed. A summary of efficiencies of STAs in removing phosphorus is given in Figure 5-11. A striking pattern in that figure is the perfor- mance of STA-1W. STA-1W performed at a high level of 74–82 percent reduc- tion from 1996 through 2002. However, the performance has declined to only 47 percent in 2006. During the 5 years of operation, the performance of STA-2

Lake Okeechobee 173 36 1800 Effective area 32 1600 Inflow Effective area, 1000 acres 28 1400 Inflow, 1000 ac-ft 24 1200 20 1000 16 800 12 600 8 400 4 200 0 0 2001 1994 1995 1996 1997 1998 1999 2000 2002 2003 2004 2005 2006 2007 Year FIGURE 5-10  Effective areas and inflow treated by stormwater treatment areas 1994–2007. Figure 5-10.eps NOTE: Average effective treatment areas reflect treatment cells temporarily off-line for plant rehabilitation. SOURCE: Data from Table 5-31 of SFWMD and FDEP (2008a). initially improved but has shown recent declines. STA-5 is showing a decline in performance (Figures 5-11 and 5-12). No reliable trend can be determined for STA-3/4, which has been in operation for only 2 years. The ongoing efforts to optimize performance of all the STAs and to rehabili­ tate STA1-W in particular are excellent examples of adaptive management. After design and construction of the STAs, their performance has been systematically monitored. Although general processes by which STAs remove phosphorus were well known at the design stage, their actual performance could be deter- mined only through a rigorous monitoring program. Several studies have been undertaken to investigate why certain parts of the STAs were performing below expectations (Pietro et al., 2008). For example, in the original flow ways of STA-2, certain regions were found to be experiencing poor performance, and an investigation has been initiated to characterize phosphorus profiles as a

174 Progress Toward Restoring the Everglades 100 Percent Reduction in Total P Concentration 90 80 70 60 50 40 30 STA 1 W STA 2 20 STA 3/4 STA 5 10 STA 6 All 0 2000 2006 2004 2005 2003 2002 2007 2001 1996 1998 1999 1997 FIGURE 5-11  Time series of annual percent reductions in concentrations of total phosphorus Figure 5-11.eps for individual stormwater treatment areas. SOURCE: Data from Table 5-31 of SFWMD and FDEP (2008a). 200 180 STA 1 W Effluent Concentrations of Total P, ppb STA 2 160 STA 3/4 STA 5 140 STA 6 120 100 80 60 40 20 0 2000 2006 2004 2005 2003 2002 2007 2001 1996 1998 1999 1997 FIGURE 5-12  Effluent concentrations of total phosphorus of five stormwater treatment areas. Figure 5-12.eps SOURCE: Data from SFWMD and FDEP (2008a).

Lake Okeechobee 175 function of the type of vegetation, time of year, and hydraulic and phosphorus loadings. Efforts are under way to rehabilitate STA-1W where reestablishment of vegetation was hindered by high turbidity. Since 1994, these STAs have removed approximately 800 mt of phosphorus from the agricultural drainage waters (Pietro et al., 2007). It is difficult, but possible, to assess long-term trends in the phosphorus sta- tus of the Everglades. This difficulty is due, in part, to the spatial ­heterogeneity in phosphorus concentrations across the landscape as well as the year-to-year climatic variability. Data for the 2003–2007 water years showed that the interior portions of each WCA met the total phosphorus criterion, while the geometric means of total phosphorus concentrations of most of the individual sites in impacted areas of the WCAs exceeded both the 10 µg/L 5-year limit and the 15 µg/L annual site limit (Table 5-3; SFWMD and FDEP, 2008a). The Environmental Protection Agency’s Regional Environmental Monitoring and Assessment Program (R-EMAP) study (EPA, 2007) was conducted to evaluate the nutrient and mercury contamination status of the Everglades. The R-EMAP sampled the ecological condition of more than 750 miles of canals and more than 3,000 square miles of freshwater marsh extending from Lake Okeechobee southward to the mangrove along Florida Bay and from the eastern urbanized edge to Big Cypress National Preserve. The program utilizes a randomly located probability-based design, which included 199 separate canal locations and 990 marsh locations. With the large number of samples and probabilistic design, it is possible to rigorously evaluate spatial and temporal patterns in water and sediment quality. The R-EMAP showed that during November 2005, 27.2 ± 7.5 percent of the Everglades Protection Area exceeded the 10 µg/L concentration of total phos­phorus. This level of contamination was a substantial improvement from the survey conducted in September 1995 in which 57.8 ± 7.8 percent of the area exceeded total phosphorus concentration of 10 µg/L. While trends TABLE 5-3  Geometric Mean of Total Phosphorus Concentrations for the Everglades Protection Area for Water Years 2005–2007 Everglades Areas Inflow Interior Refuge 65.9 11.1 WCA-2A 26.2 14.8 WCA-3A 24.0   9.4 Park   9.8   5.8 NOTE: Concentrations are µg/L. SOURCE: Data from SFWMD and FDEP (2008a).

176 Progress Toward Restoring the Everglades in surface water concentrations are encouraging, soil concentrations of total phosphorus showed a contrasting pattern. The CERP has established a restora- tion goal of decreasing the areal extent of the Everglades with total phosphorus concentrations in soil > 500 µg/g, while maintaining or decreasing long-term average concentrations to 400 µg/g or less. The 2005 R-EMAP showed that 24.5 ± 6.4 percent of the Everglades Protection Area exceeded 500 µg/g and 49.3 ± 7.1 percent exceeded 400 µg/g total phosphorus in soil. These values compare with the 1995 results, which showed that 16.3 ± 4.1 percent exceeded 500 µg/g and 33.7 ± 5.4 percent exceeded 400 µg/g total phosphorus in soil. This analysis suggests that although surface water concentrations of total phosphorus in the Everglades have improved markedly over the 10-year period 1995–2005, soils have experienced increased phosphorus contamination. Data for 2007 indicate that the annual volume-weighted concentration of total phosphorus in the outflow for all STAs was 58 µg/L, with values ranging from 22 µg/L for STA-3/4 to 192 µg/L for STA-5 (Figure 5-12; SFWMD and FDEP, 2008a). This annual volume-weighted mean is above the 50 µg/L established in 1992 for the Interim Consent Decree for STA outflow and well above the 10 µg/L criterion of total phosphorus for the Everglades Protection Area. Given the phosphorus loading to the STAs and their long-term removal efficiency, it seems unlikely that the current configuration will allow for the 10 µg/L geometric mean criterion to be achieved. To decrease the loading of phosphorus into the Everglades and ultimately to achieve the total phosphorus criterion, the STA area needs to be expanded north of the Everglades Protection Area to allow for greater capacity for phosphorus removal, and improvements are needed in watershed management practices to decrease the inputs of phosphorus to the STAs. Addi- tionally, improvements in the long-term phosphorus-removal efficiency of the STAs are needed. The STAs were designed and are largely being optimized to decrease the transport of total phosphorus to the Everglades, but another waterborne con- taminant of concern is sulfate because of its role in the methylation of mercury (Benoit et al., 2003). Gilmour et al. (2007) found that during high water, sulfur accumulates in the STAs under reducing conditions, and between 10 and 33 percent of inlet sulfate was retained. However, under drought conditions large quantities of sulfate can be released and subsequently transported to the Ever- glades. The drying and rewetting cycle of the STAs can also stimulate methylmer- cury production (Benoit et al., 2003). Thus, an objective for STA optimization is to increase the removal of sulfur, without net production of methylmercury to downstream drainage water (Rumbold and Fink, 2006).  See http://www.evergladesplan.org/pm/recover/eval_team_perf_measures_.aspx.

Lake Okeechobee 177 Need for System-wide Accounting for Phosphorus and Other Contaminants The current monitoring and assessment program for components of the Lake Okeechobee system is rich in detail and provides good indicators of performance (SFWMD and FDEP, 2008a); Chapters 3–5 and 10 of that report provide an impressive array of information about inflows, outflows, water ­quality, in-lake conditions, phosphorus-removal efficiencies in the STAs, and special investiga- tions. Descriptions of the numerous monitoring and experimental ­studies provide considerable insights into successful operations and those that are experienc- ing less than desired outcomes. Although the performance and water quality of individual components are described in considerable detail, there is a need to better integrate and synthesize this information in the context of the entire system. For example, a comparison of reported phosphorus removals from the STAs (Pietro et al., 2008) with phosphorus loads to the EAA from water inflows (Van Horn et al., 2008) leads to the conclusion that the STAs have been remov- ing a mass of phosphorus since 2001 that is approximately the same as the load on the EAA. SFWMD and FDEP (2008a) report very high phosphorus loads from Lake Okeechobee in 2005 and 2006, but what is the fate of this phosphorus down- stream? The mass of phosphorus leaving the STAs in 2006 and 2007 declined sharply from 86.9 mt in 2005 to 61.7 mt in 2007. Is real progress being made, or is the problem being either stored for future resuspension or simply discharged through the canals? Despite the generous detail provided for various components of the system (e.g., lake water phosphorus concentrations and loads, STA outflow concen- trations), the lack of integration of all the reports is a significant barrier to an evaluation of overall progress toward understanding and managing phosphorus loads to the Everglades Protection Area. By examining several components inde- pendently, it is possible to draw distinctly different conclusions about progress or the lack thereof: in terms of phosphorus, Lake Okeechobee conditions are deteriorating; in Everglades National Park, they might even be improving. This example illustrates why an annual system-wide accounting of water, phosphorus, and other contaminants (sulfur, mercury, and nitrogen) should be conducted. Such an integrated material balance would facilitate assessments of the role of the various water storage projects on phosphorus and nitrogen loading, as well as assessments of the subsequent impacts these management options would have on nutrient transport to the Everglades and the estuaries. Without a more c ­ omplete accounting of inflows, outflows, storage, and extraction of water, phos- phorus, and other contaminants for each component and how the flows from various components are related to each other, it is not clear that one can trace the mass of materials through the system. A comprehensive system-wide material

178 Progress Toward Restoring the Everglades balance analysis should be done for water and total phosphorus, as well as other critical contaminants that impact the Everglades ecosystem (i.e., sulfur, mercury, nitrogen). The transport and cycling of elements (e.g., phosphorus, carbon, sulfur) are generally closely coupled with one another (e.g., inputs of sulfur influence the transport and fate of phosphorus and mercury), and thus comprehensive material balances of contaminants of concern and associated major constituents will provide insight on ecosystem response to perturbations. Increasing Water Storage A fundamental premise of the CERP is that significantly increased water s ­ torage is needed to improve the condition of the South Florida ecosystem, includ- ing Lake Okeechobee, the estuaries, and the remnant Everglades ecosystem. As discussed previously in this chapter, modifications to the system (e.g., levees, canals, lake operations) have reduced the amount of water stored naturally in the ecosystem. As a result, some parts of the ecosystem are water starved while other parts are submerged, and the natural timing and amplitudes of highwater and drying events have been severely disrupted. Construction of storage for water in the Lake Okeechobee region is the single largest component of CERP and is proposed primarily in two forms: surface reservoirs and aquifer storage and recovery (ASR) wells. The Yellow Book plan proposed to provide approximately 5.5 MAF of new water storage, of which approximately 4 MAF can be attributed to ASR systems (assuming 30 percent injection loss) (NRC, 2005). ASR pilot projects are currently under way to address technical feasibility issues associated with ASR (NRC, 2001, 2002a). Two ASR pilot project systems have been constructed and are about to begin cycle testing. “To date, no ‘fatal flaws’ have been uncovered…that might hinder the implementation of CERP ASR” (SFWMD and USACE, 2008), but the final technical ASR program assess- ment based on the operation of the pilot systems is not anticipated until 2012. The high costs of ASR, however, have caused SFWMD leaders to publicly ques- tion the scale of the proposed ASR effort (King, 2008). The ASR contingency plan still has not been completed, and therefore, discussions of alternative water storage options have been repeatedly postponed until this document is released. Meanwhile, some stakeholders question whether the CERP, even with ASR, provides sufficient storage to support rehabilitation of the estuaries and Lake Okeechobee, given uncertainties in future climate and precipitation patterns (Audubon of Florida, 2007).

Lake Okeechobee 179 Early CERP Storage Projects A number of CERP projects that are designed to increase water storage and benefit Lake Okeechobee and the northern estuaries are under way. • The C-43 Basin Storage Reservoir (Figure 3-2, No. 1) (170,000 acre- feet) is intended to improve the quantity and timing of freshwater flows to the C ­ aloosahatchee Estuary by holding water to avoid excessive discharges and releasing water to maintain salinity gradients in the estuary. • The C-44 Basin Storage Reservoir (Figure 3-2, No. 8) (50,600 acre-feet) and STA are components of the larger Indian River Lagoon-South restoration project and are designed to decrease and attenuate excess water flow and reduce the salinity impacts on the St. Lucie Estuary. A 6,300-acre STA will capture and treat some or all of the discharge from the reservoir before it enters the St. Lucie Canal and flows to the St. Lucie Estuary and Indian River Lagoon. • The Indian River Lagoon South project (Figure 3-2, No. 8) will pro- vide 195,000 acre-feet of water storage in four reservoirs and three natural s ­ torage areas to benefit the St. Lucie Estuary. The project also includes STAs and h ­ abitat restoration initiatives (e.g., muck removal in the estuary), described in Box 3-1. • The North Palm Beach County project (Figure 3-2, No. 13) includes a water storage reservoir (48,000 acre-feet), intended to improve the timing and deliveries of flow to the Lake Worth Lagoon and Loxahatchee Estuary, enhance hydroperiods in the Loxahatchee Slough, and increase base flows to the North- west Fork of the Loxahatchee River. This project also includes habitat restoration and water treatment components. • Site 1 Impoundment (Figure 3-2, No. 2) (13,280 acre-feet) is intended to reduce water demands on Lake Okeechobee and the Arthur R. Marshall L ­ oxahatchee National Wildlife Refuge. • The Everglades Agricultural Area Storage Reservoir, Phase 1 (Figure 3-2, No. 14) (190,000 acre-feet) is expected to moderate high stages in Lake Okeechobee and discharges to the estuaries. These projects are among those scheduled for early implementation in the CERP (see Figure 3-2 for project locations). The C-43 and C-44 reservoirs, the EAA Phase 1 Reservoir, and the Site 1 Impoundment projects were all included under the state of Florida’s Acceler8 program. Also, the L-8 reservoir in the North Palm Beach County project was expedited by the state under a separate initiative. Construction is under way on the C-44 reservoir, the EAA Phase 1 Reservoir, and the L-8 reservoir (status reports for these projects are provided in Table 3-1). The

180 Progress Toward Restoring the Everglades Indian River Lagoon-South and the Site 1 Impoundment projects were congres- sionally authorized in the 2007 Water Resources Development Act. A number of issues have emerged as a result of technical review and stake- holder input with regard to the degree to which the CERP projects will achieve restoration goals. First, the storage capacity of the CERP plan, including ASR, is not large enough to detain peak freshwater discharges—such as resulted from the hurricanes of 2004 and 2005—sufficiently so as to prevent impacts from high flows into the estuaries. The impacts of excessive freshwater discharges to the estuaries could be further alleviated if more of the Lake Okeechobee outflow were allowed south through the EAA to the southern Everglades. However, as discussed previously, this is constrained by seepage management issues and water quality requirements in the Everglades, as well as flow capacity into Everglades National Park as facilitated by the Modified Water Deliveries to Ever- glades National Park (Mod Waters) project (see Chapter 4). Also, unmanaged flows from the Caloosahatchee watershed rather than from Lake Okeechobee may be significant (Figure 5-7) and may require additional efforts by landown- ers to store water. Second, there may be conflicts between human and environmental demands on these water storage reservoirs once they are operational. During dry seasons and droughts, demands to deliver fresh water from the reservoirs for agricultural and municipal water uses may result in inadequate flows to the estuaries to maintain desired salinity gradients or inadequate lake levels to support the lake biota. Meeting those human demands may come at the expense of meeting envi- ronmental freshwater requirements (see Chapter 2). Also, several of the reservoirs are intended to support recreational uses, including boating and fishing. Once established, recreational users may oppose management actions, including water level fluctuations and drainage, required to achieve environmental benefits. Finally, the water quality of this new water and potential adverse effects on the ecosystem need to be carefully considered. STAs are not included for the C- 43 reservoir as they are for the Indian River Lagoon-South reservoirs. This deep- water reservoir is not expected to reduce phosphorus or nitrogen concentrations greatly because of its lack of macrovegetation, frequently limited residence time, and susceptibility to sediment resuspension; thus, nutrient loading to the Caloosahatchee Estuary may exceed that needed to achieve water quality objec- tives. A third draft of the EAA Reservoir Phase 1 project is now in development, primarily due to inadequate plans to address the water quality implications of the reservoir on the Everglades ecosystem.

Lake Okeechobee 181 Changes in Lake Operations The USACE manages water levels in Lake Okeechobee through operation of a series of structures that can release water to the Caloosahatchee Estuary to the west, the St. Lucie Estuary to the east, and to outlet canals to the south of the lake. Safety concerns regarding the Herbert Hoover Dike, combined with high lake ­ levels over the period 2003–2005, led to a number of damaging high water releases to the estuaries. Therefore, the USACE launched a review of the lake operating rules (called the Water Supply and Environmental [WSE] regulation schedule), which were adopted in 2000 and based on a historically drier time period. Given the constraints on lake water discharges, there is a limited range of options for modifying the operating policy. Large releases to the Everglades eco- system will be possible only with the appropriate conveyance and seepage man- agement structures in place and reduced phosphorus concentrations, either from additional STAs or improvements to lake water quality. In the Lake Okeechobee Regulation Schedule Study, several alternatives were evaluated using the South Florida Water Management model, with 36 years’ worth of historical records. The model was used to calculate stage duration curves (relative frequencies at which the lake is at or below stages varying from 8 to 18 feet) for a range of alternatives and compared to the WSE (No Action). At all relative frequencies, all of the pro- posed alternatives resulted in about a 1-foot decline in surface elevation compared to the WSE, thus reducing the total storage capacity of the lake by about 450,000 acre-feet. The alternatives had a positive effect on low flows to the estuaries, but they had no impact on very high flows (Table 5-4) (USACE, 2007b). As a result of this study, a new regulation schedule was approved by the USACE in April 2008, and a new operation regime is now being implemented for an interim period. The new operation schedule consists of complex decision tree where releases are governed by hydrologic conditions at selected locations throughout the system. The new schedule incorporates improved climate fore- TABLE 5-4  Comparison of the Frequencies of Flows into the Caloosahatchee Estuary under the Lake Okeechobee Regulation Schedule and the “No Action” Alternative for a 36-Year Simulation No. of Months in Flow Ranges Ranges of Flow (cfs) No Action Tentatively Selected Plan < 450 198 131 450–2500 160 237 2500–4500   45   35 > 4500  �� 29  �� 29 SOURCE: http://www.saj.usace.army.mil/cco/docs/lorss/LORSS_PM_Pres-6Aug07.pdf.

182 Progress Toward Restoring the Everglades casts as part of decision trees, and it allows longer and lower rates of release to the WCAs and the estuaries to reduce the impact of sudden pulse releases. Water Storage in the Northern Everglades The preferred plan for the Northern Everglades and Estuaries Protection Program includes water storage capacity ranging from 0.9 to 1.3 million acre- feet, including three reservoirs upstream of the lake, three large reservoir-assisted STAs, and a variety of other storage projects. The plan (SFWMD et al., 2008), however, does not provide full details on all the potential projects. Three non- CERP storage projects are described, with a combined volume of 441,000 acre- feet; three reservoir assisted STAs, with a capacity of 474,000 acre-feet, are listed in Table 5-4; and a variety of other specific projects have a combined capacity of 102,000 to 139,000 acre-feet. The balance of 250,000–280,000 acre-feet is not specified. Only 29 percent of the total storage capacity in the plan was represented by management measures with the highest level of implementation certainty (Level 1; see Table 5-1). Sixty-nine percent of the remaining planned storage capacity reflects Level 4 management measures with low implementation and projected benefits certainty. The Northern Everglades Regional Simulation Model was used to examine the effects of the alternative plans on flows in the watershed compared to cur- rent base conditions and future base conditions without additional reservoirs. If these projects in the preferred plan are realized, there would be substantial improvement in all performance measures listed relative to current and future base conditions without those projects (Table 5-5). Synergistic Opportunities from the Repair of the Herbert Hoover Dike As discussed in the previous section, concerns about the structural integrity of the Herbert Hoover Dike currently limit the capacity to store water at higher stages in Lake Okeechobee, which creates more frequent high and damaging discharges to the northern estuaries. Optimal lake levels, however, are also determined by the desire to enhance conditions for lake biota and protect the lake’s littoral zone. Nevertheless, rehabilitation of the Herbert Hoover Dike may offer synergistic opportunities for creating additional CERP storage and man­aging water levels for the benefit of the littoral zone, and the costs, benefits, and hydrologic and ecological viability of these options should be considered in any analysis of CERP storage alternatives. Alternative Dike Configurations. Localized outward movement of the Herbert Hoover Dike was considered in the Yellow Book but not adopted. The concept

Lake Okeechobee 183 TABLE 5-5  Performance Measures for Water Quantity Current Future Preferred Target Base Base Plan Lake Okeechobee (percent of the time) Extreme Low Lake Stage 100 91.7 94.1 99.1 Extreme High Lake Stage 100 83.6 87.9 95.4 Below Envelope—Weekly Average 100 61.0 66.0 89.2 Above Envelope—Weekly Average 100 58.0 65.9 80.3 Caloosahatchee Estuary (number of months out of 432) Mean Monthly Flow > 2,800 cfs  3   82 55 51 Mean Monthly Flow > 4,500 cfs  0   38 25 18 Number of months Lake Okeechobee   regulatory releases >2,800 cfs  0   21 13  9 Mean Monthly Flow < 450 cfs  0 190 32 18 St. Lucie Estuary Mean Monthly Flow > 2,000 cfs and < 3,000 cfs  0   37 38 33 Mean Monthly Flow > 3,000 cfs  0   28 21 18 Mean Monthly Flow < 350 cfs 31 134 26 15 Water Supply (percent of target) Annual Percent Demand not Met (%) 0 4.7 4.2 2.4 Lake Okeechobee Service Area Mean Annual   Percent Demand Not Met (%) 0 4.4 4.6 1.5 SOURCE: Data from SFWMD et al. (2008). entails moving the dike outward in some locations so that the littoral zone can also move and support essential biotic functions in a different location of the lake. After all, the littoral zone did not exist at its current location historically; rather, it developed based on the management of the lake at lower water levels. An expanded dike configuration, if politically and societally feasible, could allow the lake to function at higher water levels once the dike has been reha- bilitated. Although this committee makes no recommendations on this option, it echoes the advice of an earlier NRC committee (NRC, 2005) to keep an open mind about various water storage options, especially if current plans for storage are more expensive or less effective than expected. Establishing a Flow Way. One option that has long been considered, and often rejected to date, is the concept of a flow way, a direct connection between Lake Okeechobee and WCA-3A to the south. With cost and feasibility of ASR still an issue, the flow way continues to appear among options for transporting water

184 Progress Toward Restoring the Everglades and has considerable advocacy among some environmental groups (e.g., A.R. Marshall Foundation, 2007). The concept involves “natural” flow of water south of Lake Okeechobee, through some areas of what is currently the EAA. Assuming a wetland environment, some water quality benefits might also accrue, although this would depend on the water depth. Some of its advantages and disadvantages as evaluated by this committee are outlined in Table 5-6. A major technical challenge is that subsidence and oxidation of peat have altered the historic land surface gradient between Lake Okeechobee and the WCAs, and some form of water management structures, including pumps, may be necessary to move the water through the region. If pumping is minimized, the storage areas themselves would need to be quite deep, functioning essentially like reservoirs. Perhaps the primary objection raised by agency evaluations is that a hydrau- lically unmanaged flow from the lake to the WCAs “would not be present in dry or even normal years” (USACE and SFWMD, 1999). The Yellow Book conclusion is that “The need for flow ways would have to be justified for other reasons rather than hydrology alone.” The A.R. Marshall Foundation (2007) argues that one such reason, apart from reestablishing the historic flow pathway, is that the flow way would be cost-effective relative to ASR by providing storage for large quantities of water in the subsided lands between the lake and the south. Of course, this assumes that a flow way, considering evapotranspiration losses, would provide storage equivalent to ASR. The biggest and most-often cited impediment to a flow way was the socio- political task of obtaining land for this project that is currently in agricultural and urban use, but this hurdle might now have been greatly reduced with the announcement by the state of Florida that it is negotiating the potential acqui- sition of 187,000 acres of U.S. Sugar Corporation land in the EAA just south of Lake Okeechobee. CERP planners now have an opportunity to consider restoration alternatives that previously were unavailable (e.g., vastly increased STAs, additional surface storage, increasing flow from Lake Okeechobee to the Everglades ecosystem during wet periods). These restoration opportunities would not be available if other kinds of devel- opment replaced agriculture as a primary land use in the EAA. Any reanalysis of the CERP should consider ways to optimize the restoration program and make it more cost-effective, while weighing the impacts of any associated trade-offs. The high costs of rehabilitating the Herbert Hoover Dike have led to sug- gestions that a spillway at some as-yet-undetermined lake level could negate the need for extensive dike repair. Flows discharged out of such a spillway might logically enter a flow way, although it is unclear as to the degree to which such flows could be integrated into CERP storage and conveyance needs, given the current water quality issues in Lake Okeechobee. CERP agencies continue to

Lake Okeechobee 185 TABLE 5-6  Positive and Negative Characteristics of a Flow Way Characteristic Advantages Disadvantages Ecosystem Creates hydrologic connection from the Transports low-quality water south into the processes Northern to the Southern Everglades. Everglades. Increases water storage capacity of the Reduces water quantity through additional ET natural system. from standing water in flow way. Mimics historic water flow path. Requires land currently in agricultural production. May provide option for treatment as it flows, Water in flow way will likely be deep over most hence acting in part as an STA. of its path if pumping costs are minimized. While sedimentation may be enhanced, wetlands vegetation growth may be inhibited. May increase habitat area available for certain Actual design is uncertain. May not be “miles species under wet and dry conditions. wide,” but rather more like a very wide canal. Contributes to “true” restoration of the Everglades. Good public perception. Potentially high releases to the flow way would reduce or eliminate damaging releases to the estuaries. Hydrologic Gravity feed from Lake O. to the WCAs. Gravity feed hampered by subsidence in EAA. issues Greatly altered topography from early 1900s. Will likely require pumps to get water out. Water flows “naturally.” Current conveyance system with pumps and hydraulic structures offers flexibility in operations. Lake O. dike renovation may offer opportunity May require compartmentalization of flow for synergistic connection with “the spillway,” way into “boxes” in order to reduce wind fetch including opportunities for costsharing. and wave setup and resultant threat to levee integrity and freeboard. Water may seep out of constraining levees into remaining EAA. Financial Cost analysis not done, but might reduce Cost of attaining additional EAA land is not costs need for some currently planned CERP documented. storage and/or additional STA construction. Alternative ASR life-cycle costs, including Will require displacing communities and energy, may be more than capital and O&M people at upstream end. costs of flow way. Flow way may have a smaller “carbon footprint.” Opportunities for cost sharing with HHD renovation.

186 Progress Toward Restoring the Everglades provide negative evaluations of the technical feasibility and cost-effectiveness of a flow way compared to current CERP plans, despite new potential cost benefits associated with the rehabilitation of the Herbert Hoover Dike (e.g., Strowd and Punnett, 2007). CONCLUSIONS AND RECOMMENDATIONS Lake Okeechobee is a critical linchpin of the South Florida ecosystem. However, the lake presently is plagued by both high and, more recently, very low water levels as well as poor water quality, especially phosphorus, that have affected its structure and functioning. The challenges of water quantity and quality in the lake have important ramifications for the entire ecosystem because the lake supports important elements of the region’s biota, and it also has the potential to serve as a major source of water storage and water supply for downstream ecosystems. This potential will become more critical if other planned and proposed sources of water storage do not become available. An integrated, system-wide view of water quality management is essential to the achievement of restoration goals for the South Florida ecosystem. Good data are available for study to understand the local dynamics of phosphorus and other contaminants, but a system-wide accounting is lacking for water and phosphorus as well as other important contaminants, such as sulfur, mercury, and nitrogen. An integrated system-wide accounting in various components of the basin (including soils, sediments, vegetation, and water) is needed to deter- mine the mechanisms of contaminant transport throughout the ecosystem—from the Kissimmee River to Everglades National Park—to assess the implications of upstream ecosystem changes on downstream habitats, to determine appropriate management actions, and to evaluate system-wide progress to improve water quality. It also is crucial to determine to what degree the current status of the lake represents a changed condition that will resist restoration. Recent water quality restoration initiatives in the Northern Everglades are not likely to achieve the stated water quality goals (40 ppb total phosphorus in the lake and 140 metric tons per year phosphorus input load) by the year 2015, and it might take decades for these goals to be met with current strate- gies. Using the “no-action alternative” to manage internal phosphorus loads in the lake is likely to delay achieving in-lake concentration goals by several decades, as concluded by the South Florida Water Management District. Also, although the Northern Everglades initiative’s technical plan identifies numerous management measures to reduce phosphorus loads and appropriately assesses the challenges and uncertainties in the proposed plan, the strategies probably are not adequate to reduce external phosphorus loads sufficiently. The Northern

Lake Okeechobee 187 Everglades initiative is appropriately focused on reducing phosphorus inputs to the lake as an initial step, but given the uncertainties associated with the cur- rent management measures, this committee judges it unlikely that the current TMDL of 140 mt of phosphorus input to the lake will be met by the year 2015. More significant remediation strategies in the lake and its watershed will prob- ably be needed to reduce the legacy phosphorus in the system and meet the TMDL goal. Although the Northern Everglades plan represents a sizable effort, it will not be easy or inexpensive to reverse the lake’s decline in water quality. One of the greatest challenges to this program may be securing the necessary funding to fully implement the initiative. The lake’s importance in the ecosystem, however, justifies significant attention from researchers and planners and justifies the devo- tion of considerable resources to the lake. In the near term, restoration planners should consider the consequences of the likely failure to achieve the phosphorus goals and develop alterna- tive approaches. Alternatives may involve significant reallocation of priorities among restoration projects and/or significant changes to water quality criteria for downstream deliveries. One structural option is to increase the number and size of STAs. Given questions concerning the long-term effectiveness of STAs in phosphorus removal, the current phosphorus loadings to the STAs suggest that their current configuration will be insufficient to achieve the 10 μg/L phosphorus criterion in the Everglades Protection Area. Meanwhile, failure to achieve the water quality goals in Lake Okeechobee will affect the condition of the lake and the northern estuaries, and it will reduce the amount of additional water that can be delivered to the Everglades ecosystem. Alternative approaches to addressing these water quality issues may involve significant reallocation of priorities among restoration projects. Restoration planners should carefully consider the needs for additional STAs, considering the opportunities that may be made available by the state’s potential land purchase in the Everglades Agricultural Area. In addition, methods of improving the long-term ability of STAs to remove phosphorus should be investigated. In-lake treatment of phosphorus may also be needed to expedite the rehabilitation of Lake Okeechobee as external loads are reduced. Given concerns about the financial and technical feasibility of aquifer storage and recovery (ASR) at the large scale proposed in the CERP, additional opportunities for water storage should be investigated, and Lake Okeechobee may be an important component of those alternatives. Several important water storage projects are under development through the CERP and Acceler8, largely intended to modulate flows to the northern estuaries, and additional opportuni- ties for water storage upstream of Lake Okeechobee are being considered within the Northern Everglades initiative. Nevertheless, alternative storage options

188 Progress Toward Restoring the Everglades should be considered as possible contingencies to ASR—the primary source of new water storage for the CERP, but for which there are concerns about financial and technical feasibility—including synergistic opportunities related to modifi- cations of the Herbert Hoover Dike. This committee makes no specific recom- mendations as to the most appropriate storage options, but it encourages CERP planners to consider a wide array of alternatives and their costs and benefits. Short-term and long-term trade-offs will be needed in the rehabilitation of Lake Okeechobee and northern estuaries. Moving appropriate volumes of water south into the Everglades and managing flows into the northern estuaries may pose conflicts with sustaining adequate water levels for the lake biota and other in-lake goals, and until the Herbert Hoover Dike is rehabilitated, the risk of its failure at high lake levels will constrain options. Given the current altered state of the whole system, goals for the lake, the northern estuaries, and other downstream interests might not be mutually compatible in all respects. As a result, trade-offs will have to be made. Modeling and adequate, reliable data will be needed to evaluate many of these trade-offs as discussed in NRC (2005) and Loucks (2006).

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This book is the second biennial evaluation of progress being made in the Comprehensive Everglades Restoration Plan (CERP), a multibillion-dollar effort to restore historical water flows to the Everglades and return the ecosystem closer to its natural state. Launched in 2000 by the U.S. Army Corps of Engineers and the South Florida Water Management District, CERP is a multiorganization planning process that includes approximately 50 major projects to be completed over the next several decades.

Progress Toward Restoring the Everglades: The Second Biennial Review 2008 concludes that budgeting, planning, and procedural matters are hindering a federal and state effort to restore the Florida Everglades ecosystem, which is making only scant progress toward achieving its goals. Good science has been developed to support restoration efforts, but future progress is likely to be limited by the availability of funding and current authorization mechanisms. Despite the accomplishments that lay the foundation for CERP construction, no CERP projects have been completed to date. To begin reversing decades of decline, managers should address complex planning issues and move forward with projects that have the most potential to restore the natural ecosystem.

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