Progress Toward Restoring the Everglades The Ninth Biennial Review - 2022 (2023) / Chapter Skim
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From page 89... ...
has recently been completed, and the first biennial report evaluating the performance of the COP is being drafted. The information available suggests that the TTFF has been effective in hitting targets for rising water in the wet season and some recession rates in the dry season (Figure 3-27)
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From page 90... ...
-- and two more in WY 2022. However, these constraints promise to be greatly reduced by the construction of a seepage bar rier along the boundary between the 8.5 Square Mile Area and Northeast Shark River Slough (Figure 3-20)
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From page 91... ...
. Because of increased flows to Northeast Shark River Slough and Taylor Slough, the COP is expected to increase hydroperiods in the adjacent marl prairie areas.
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From page 92... ...
, compared to the stage at S-333, reflecting the stage of southern WCA-3A. High total phosphorus concentrations in the dry season resulted in an exceedance of water quality limits when dry season flows were relatively high in WY 2019 and WY 2021, but not in WY 2018 and WY 2020 when dry season flows were negligible.
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From page 93... ...
SOURCE: USACE, 2020b. habitat suitability in some areas of subpopulation A that currently are too wet, particularly in areas near Shark River Slough (northern AX in Figure 3-29)
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From page 94... ...
The available evidence suggests that this is the case, for both hydrology and the changes in vegetation representing the anticipated ecological response to altered hydrology that impacts sparrow habitat suitability. Available vegetation mapping and hydroperiod data enable a comparison between average conditions during the incremental testing phase of the COP (data have been collected in 2017-2020 for Shark River Slough and in 2018 for Taylor Slough)
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From page 95... ...
Restoration Progress 95 FIGURE 3-30 Change in 4-year mean discontinuous hydroperiod between 2003-2005 and 2017-2020 survey periods at vegetation survey sites in CSSS subpopulations A, B, C, E, and F
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, almost no conversion of wet prairie to marsh has occurred (Figure 3-31) and the birds occupy the full range of wet prairie habitats (Figure 3-32)
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From page 97... ...
Restoration Progress 97 FIGURE 3-31 Change in vegetation types in habitat in CSSS subpopulations A, B, C, E, and F between 2003-2005 and 2017-2020 surveys. NOTES: M-M = one marsh vegetation type to another marsh vegetation type, M-WP = marsh vegetation type to wet prairie vegetation type, WP-M = wet prairie vegetation type to marsh vegetation type, WP-WP = one wet prairie vegetation type to another wet prairie vegetation type.
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From page 98... ...
98 Progress Toward Restoring the Everglades FIGURE 3-32 Map showing the vegetation types at the CSSS census sites surveyed between 2017 and 2020 and the number of birds observed at each point during the annual sparrow surveys over 3 years (2017-2019)
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From page 99... ...
The above examination of changes in marl prairie habitats in no way constitutes an assessment of the performance of the COP, or of the impact of projects such as Mod Waters, C-111 South Dade, or C-111 Spreader Canal. Nor is it an assessment of their contributions toward achieving restoration benefits.
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100 Progress Toward Restoring the Everglades FIGURE 3-33 Vegetation types in the habitat of CSSS subpopulation D in (A)
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The footprint of Phase 1 of the BBCW Project is small; its goals are to restore about 400 acres of freshwater wetlands and increase water flows in another approximately 2,000 acres in three geographically distinct components: the Deering Estate Component, just north of the Biscayne Bay National Park, and the Cutler Wetlands and L-31E Flowway Components, portions of which are within the national park (Figure 3-34)
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From page 102... ...
102 Progress Toward Restoring the Everglades FIGURE 3-34 Biscayne Bay Phase 1 Coastal Wetlands Project locations. SOURCE: Charkhian, 2022a.
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The S-700 pump station on the C-100A Spur Canal within Deering Estate is designed to restore historic freshwater flows through the Cutler Drain Slough and into the coastal wetlands, reducing near-shore salinity. The hydrologic goal was to redirect up to 100 cfs of water from the C-100A Spur Canal to the coastal wetlands (Figure 3-35)
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From page 104... ...
. In WY 2020 and WY 2021, the S-700 pump station diverted 30,951 and 36,948 AF to the coastal wetlands that would have otherwise been discharged through the S-123 structure (Charkhian, 2022b)
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From page 105... ...
, although by the committee's next report, the effects of the new pump stations on wetland and near-shore salinity should be apparent. CERP Projects in Planning: Biscayne Bay and Southeastern Everglades Ecosystem Restoration The ultimate goal of the BBSEER Project is ecosystem restoration of wetland and near-shore habitats in Biscayne Bay, Card Sound, Barnes Sound, the Model Lands, Southern Glades, and other wetlands adjacent to these water bodies consisting of low-lying marl prairie, sawgrass wetlands, and mangroves.
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6 and Southern Glades areas, reduce wet season flows to C-111, and decrease potential in Figure 3-37) flood risk in the lower south Miami-Dade County area.
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Restoration Progress 107 FIGURE 3-37 BBSEER Project footprint with locations of Yellow Book projects integrated into the planning effort. SOURCE: Foster, 2021.
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Timing and distribution of flow sources to Biscayne Bay; 7. Resiliency (see Chapter 5, Box 5-3)
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From page 109... ...
, is rehydrating Northeast Shark River Slough and appears to be facilitating increased flow into Everglades National Park. The rehydration of Northeast Shark River Slough represents the largest step yet toward restoring the hydrology and ecology of the central Everglades.
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From page 110... ...
Water quality is an ongoing concern that could potentially constrain prog ress on several fronts, including the COP and the CEPP. Increased dry season flows are a specific project objective for the CEPP, but new infrastructure and recent operational changes under the COP that have facilitated higher dry season flows have also resulted in total phosphorus exceedances.
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From page 111... ...
, a mid-course assessment of expected CERP outcomes that accounts for newly identified constraints in storage and incorporates the latest climate change science would inform future management decisions regarding restoration planning, funding, sequencing, and adaptive management. The SFWMD has implemented a rigorous approach to address uncertainties associated with ASR in the Lake Okeechobee Watershed Restoration Plan.
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From page 113... ...
Wet season, which receives 70 percent of the total hydraulic and phosphorus loads, is considered to occur from May 1 to October 31, and dry season is considered to occur from November 1 to April 30. All the monitoring data collected since the construction of STAs are reported on a WY basis.
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From page 114... ...
. Both cases make it clear that discharging water into the Everglades Protection Area that does not comply with water quality standards is a violation of the Clean Water Act.
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From page 115... ...
Long-term limits were to be achieved by 2002 (later amended to 2006) including annual flow-weighted concentration goals in Shark River Slough of no more than 13 ppb in a dry year and 8 ppb in a wet year, and the long-term concentration limit for Taylor Slough and the Coastal Basins was set at 11 ppb.
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From page 116... ...
deficiencies in meeting its water quality standards and articulated that "the nar rative and numeric nutrient criteria in the State's water quality standards are not being met for the Everglades Protection Area."9 The Amended Determination was intended to provide an enforceable plan for ensuring that the water entering the Everglades Protection Area from the EAA and the C-139 Basin complies with the previously adopted narrative and numeric phosphorus criteria for the Everglades Protection Area (FAC §§ 62-302.540)
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From page 117... ...
STA Water Quality and CERP Progress 117 FIGURE 4-1 Location of water quality monitoring stations used to assess water quality conditions in the Everglades Protection Area and mean TP concentrations for WY 2021. For WY 2021, 83 percent of interior marsh sites had annual geometric mean TP concentrations in water of less than or equal to 10 µg/L and 89 percent had annual geometric means of 15 µg/L or less.
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From page 118... ...
. Timely WQBEL attainment affects CEPP implementation progress for two major project elements: CEPP North and CEPP EAA Reservoir (see Chapter 3 and Figure 3-19)
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. The STAs are grouped into three flow paths: the Eastern Flow Path (STA-1E and STA-1W)
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to Construction completion expected in 2024 Improvements the west Subregional Source Reduce inflow loads from Pilot projects completed in 2015 and 2017; Controls hotspots in the basin conceptual project planning ongoing Central Flow Path A-1 FEB Attenuate flow into STA-2 and Construction completed 2015, now operational STA-3/4 Western Flow Path STA-5/6 Internal Improve the performance of Construction completed 2020, now in optimization Improvements STA-5/6 period C-139 FEB Attenuate flow into STA-5/6 Construction completion expected in 2023 SOURCES: Data from Chimney et al., 2022a; Shuford et al., 2022. However, once the Miami Canal is plugged, if inflows do not meet the WQBEL, the redistribution of water as sheet flow through WCA-3A could increase TP concentrations in interior areas not previously affected (see Figure 4-1)
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From page 121... ...
ll features of the state's Restoration Strategies must be completed and meet state water quality standards prior to initiating any operations which would allow water from the Federal EAA project to enter any of the state's Restoration Strategy facilities." Until the WQBEL is met for the Restoration Strategies STAs, "the EAA reservoir may only be operated to flow the amount of water that the new EAA A-2 STA alone can treat to meet all federal and state water quality standards, as well as any additional treatment necessary for passage of water to Everglades restoration" (USACE, 2020c) .11 Under this policy, before the A-2 Reservoir is allowed to operate at full capacity, the prior 5 years of data 10 Following release of the prepublication version of the report, this paragraph was modified to correct its description of the compliance process.
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Modeling for the EAA Reservoir planning process calculated that the A-2 STA could treat an average of 162,100 AF/year (out of the 370,000 AF/year that the CEPP was projected to provide on average) and the remaining 207,900 AF/year would be treated by STA-2 and STA-3/4 (SFWMD, 2018a)
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From page 123... ...
In the balance of this chapter the committee turns its attention to a review of the underlying science, engineering, design, and operations of the STAs and a discussion of the progress to date under Restoration Strategies, with the goal of helping inform the state's efforts to meet the WQBEL criteria by 2027. OVERVIEW OF STAS Constructed treatment wetlands are used globally to remove nutrients and other contaminants from inflow waters and to maintain desired outflow water quality (Kadlec and Wallace, 2009; Vymazal, 2022)
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. In the soil and water column, phosphorus is present in organic and inorganic forms, which can be present as dissolved and/or particulate forms (Box 4-3; Appendix B)
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Particulate phosphorus (PP) fractions are considered those in water that do not pass through a 0.45 µm filter: Particulate inorganic phosphorus (PIP)
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From page 126... ...
In treatment cells containing SAV, underwater photosynthesis and primary productivity promote alkalization and calcium carbonate (CaCO3) formation in the water column that is deposited as a fine particulate sediment.
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From page 127... ...
Small areas with deep water zones near STA inflows are sometimes colonized by FAV. Although FAV can assimilate phosphorus in the biomass, it is generally undesirable in STA operations because it spreads rapidly, depletes water column oxygen, lowers pH, and interferes with the underwater growth of shoots of EAV.
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From page 128... ...
King, SFWMD. and function of periphyton, the soil from the PSTA cell is initially removed down to the underlying limestone caprock to reduce potential internal phosphorus loading from existing soil.
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Dense vegetation communities near STA inflows are designed to reduce the water velocity, creating a quiescent flow regime that facilitates particulate settling and nutrient removal. High flows or intense wind and storm events can mobilize floc and increase TP in the water column.
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From page 130... ...
and receive inflows from the EAA and Lake Okeechobee, with inflow TP concentrations to STA-2 and STA-3/4 approximately 50 percent lower than those to the other STAs (Table 4-2) .14 STA-3/4 has shown consis tently impressive performance over the period of record and has maintained effluent phosphorus concentrations consistent with the WQBEL requirements during the recent 6 years (WY 2017-2022)
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From page 131... ...
and phosphorus loading rates are much larger than those of the Central Flow Path (Table 4-2)
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From page 132... ...
Neither STA has experienced average annual discharges below 19 μg/L during the past 6 years. Significant work is now under way through Restoration Strategies to address performance issues, including efforts to mitigate hydraulic short circuiting, excessive dry downs, and high phosphorus loading rates.
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From page 133... ...
Additional concepts are expected to be developed as these discussions continue." In summary, significant progress is under way in STA expansion and refurbishment in the Eastern Flow Path, but no progress in reducing loads is apparent through additional Restoration Strategies subregional source control practices despite a decade of effort. STA-5/6 (Western Flow Path)
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From page 134... ...
Assessment Across All STAs Efforts undertaken as part of Restoration Strategies are expected to improve the performance of all STAs. The impressive performance of STA-3/4 shows that sustained discharge with TP concentrations below 13 μg/L is possible, especially if associated with low phosphorus inflow concentrations and loading rates.
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From page 135... ...
ever, the challenge of meeting the WQBEL starting in WY 2027 is substantial. A helpful way to illustrate key challenges across the different STAs is to calculate phosphorus treatment efficiency based on either average flow-weighted mean inflow and outflow TP concentrations or inflow and outflow TP loads.18 Phosphorus treatment efficiency of STAs based on average inflow and outflow concentrations over the most recent 6 years (WY 2017-2022)
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From page 136... ...
Efforts are also under way through Restoration Strategies to reduce phos phorus loading rates by increasing the STA treatment area in the Eastern Flow Path. Moreover, Restoration Strategies envisioned efforts to reduce phosphorus loads through subregional source control efforts, although no source reduction projects have been implemented.
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