Progress Toward Restoring the Everglades The Second Biennial Review - 2008 (2008) / Chapter Skim
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4 Mod Waters
4 Mod Waters
Pages 109-142
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From page 109... ...
Nearly 50 years of water blockages and diversions have altered and impaired Shark River Slough, in the heart of Everglades National Park, making the northeastern side too dry and the western side too wet. Mod Waters had a simple goal: offset the continuing adverse effects of these flow diversions by restoring more natural water flows into Everglades National Park and, thereby, set the stage for the Comprehensive Everglades Restoration Plan (CERP)
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From page 110... ...
; inset map © International Mapping Associates. OBJECTIVES OF THE MODIFIED WATER DELIVERIES PROJECT Roads and canals have long affected water flow into the Shark River Slough in Everglades National Park, but the construction of the water conservation areas (WCAs)
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From page 111... ...
The Mod Waters project was authorized in 1989 as part of the Everglades
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From page 112... ...
. If successfully completed, Mod Waters will provide significant restoration in Everglades National Park by increasing the flow of water into Northeast Shark River Slough.
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From page 113... ...
Gamble, National Park Service, personal communication, 2006, and K Taplin, U.S.
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From page 114... ...
to supplement water deliveries to south Dade and ENP 1970 Minimum Water Delivery Required a minimum of 315,000 acre-feet of Schedule (PL 91-282) water deliveries to ENP each year, with a fixed monthly allotmenta 1983 ENP Seven-Point Plan issued Reduce the impacts of high S-12 regulatory flows on West Shark River Sloughb 1983-1999 Experimental Water Deliveries Test different water delivery schedules to restore Program (PL 98-181)
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From page 115... ...
Conference Report, "Without a change in water delivery to the Park, restoration of the Everglades, and many of the projects authorized as components of the Comprehensive Everglades Restoration Plan (CERP) in 2000, will not succeed." Since congressional authorization nearly 20 years ago, the Mod Waters project has been plagued by complex and difficult obstacles.
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From page 116... ...
It exemplifies the con flicts among stakeholders that have plagued the Mod Waters project and those that may face the CERP as it moves forward. Stakeholders with the potential to be impacted by the CSOP include Everglades National Park (ENP)
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From page 117... ...
are required to allow greater water inputs to Northeast Shark River Slough, and higher water levels can adversely affect the stability of the road base given modern traffic loads and speeds. Much of the controversy surrounding the Tamiami Trail component centers on the road design necessary to accomplish hydrologic restoration "to the extent practicable" while protecting the integrity of the roadbed and also minimizing the likelihood of flooding of tree islands within WCA-3B.
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From page 118... ...
side of Tamiami Trail to flow through the culverts beneath the highway -- is shown in Figure 4-5. Given sufficient head (or water elevation above the downstream elevation of Shark River Slough)
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From page 119... ...
would allow the required Mod Waters flows to pass under the road at a lower stage in the L-29 canal than with the culverts alone, thereby reducing the required height of and improvements to the road and minimizing adverse high-water-level effects on tree islands once Northeast Shark River Slough is reconnected with WCA-3B.
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From page 120... ...
Sheet flow can still be achieved downstream of an unbridged road, although there would be some as-yet-unspecified distance of unnatural flow downstream of the culverts that may alter native habitats. As CERP projects, particularly Decomp, were being developed in the late 1990s, it became clear that reevaluation of Tamiami Trail modification plans was needed to ensure consistency between Mod Waters and CERP objectives (USACE, 2003)
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From page 121... ...
TABLE 4-2 Post Authorization Progress of the Mod Waters Project Conveyance, Seepage, and Tamiami Trail Modifications 8.5-Square-Mile Area (SMA) Operating Plan Date Event Purpose / Outcome Event Purpose / Outcome Event Purpose / Outcome 1992 Design proposed Includes raising the Design Includes a pump Design Includes gated culverts in General Design road in the vicinity of proposed in station, canal, and a proposed in in the L-67A, spillways Memorandum S-334, but no additional GDM levee around entire GDM in L-29, raising of 2 (GDM)
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From page 122... ...
TABLE 4-2 Continued 122 Conveyance, Seepage, and Tamiami Trail Modifications 8.5-Square-Mile Area (SMA) Operating Plan Date Event Purpose / Outcome Event Purpose / Outcome Event Purpose / Outcome 1998 SFWMD Recommends total Review Team buyout of 8.5 SMA Study Suspends further action Legal challenge to SFWMD review team study 1999 FL Governor FWS jeopardy Ends Experimental Water replaced opinion on Deliveries program at SFWMD Cape Sable iteration # 7 governing seaside board sparrow SFWMD and DOI requested USACE to examine alternatives for 8.5 SMA 2000 USACE Plan includes protective Interim Emergency Deviation in finalizes and levee with acquisition of Structural and water deliveries to ENP to approves the western third of the Operational protect CSSS revised 8.5 SMA Plan project (ISOP 2000)
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From page 123... ...
Mod Waters and C-111 EIS initiated (South Dade) continued 123
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From page 124... ...
the CSOP 108-7) Advisory Team Tamiami Trail Halts Mod Waters GRR withdrawn progress because no agreement could be reached with FDOT 2005 Tamiami Trail Recommended 8.5 SMA USACE begins CSOP Leads to some Revised GRR modifications to Record of construction of Advisory modifications (RGRR)
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From page 125... ...
for Tamiami Trail 2008 USACE Expected USACE Necessitates that the recommended construction recommends CSOP be revisited 1-mi eastern completion 1-mi eastern bridge with road bridge in modifications to Tamiami Trail allow water levels modifications of 8.5 ft 125
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From page 126... ...
of water flow, dividing the flow from WCA-3A, assuming that 55 percent of this flow would be moved into Northeast Shark River Slough. The specific mechanism of conveyance was not considered; thus, the results were not limited by the capacity of current conveyance structures (T.
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From page 127... ...
If completed, this plan will provide important steps toward restoration in Everglades National Park by increasing the volume of water entering Northeast Shark River Slough by at least 163,000 acre-feet per year over the current level (or an increase of at least 92 percent over cur
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From page 128... ...
However, after two decades of effort, achieving some benefits from Mod Waters is critical for the overall CERP pro gram, especially in light of continuing deterioration of the Northeast Shark River Slough ecosystems. The recommended plan does not provide more water into Everglades National Park than before; it only redistributes the 1983–2006 water coming out of WCA-3A according to a 45–55 percent distribution in West Shark River
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From page 129... ...
will provide adequate hydraulic capacity to pass higher overall flows into Everglades National Park while maintaining the 45–55 percent distribution between West Shark River Slough and Northeast Shark River Slough. Real estate issues and higher construction costs at the western location were two main factors that influenced selection of the eastern bridge location (alternative 3.2.2.a)
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From page 130... ...
Flood Mitigation in the Eastern Everglades Developed Areas Control of seepage and flooding in the eastern Everglades developed area, especially the 8.5-square-mile area, has been a highly controversial component of the Mod Waters project. This component provides flood mitigation to the urban and agricultural areas within the 8.5-square-mile area associated with the higher water levels created by Mod Waters in the restored Northeast Shark River Slough of Everglades National Park (Figures 4-3 and 4-7)
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From page 131... ...
. After additional court challenges from 8.5-square-mile area residents, the USACE was directed by Congress to acquire the property necessary to carry out Alternative 6D and to provide flood protection in the remaining residential area with a protective levee.
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From page 132... ...
Conveyance and Seepage Control The conveyance and seepage control features of Mod Waters were planned to move water from WCA-3A to WCA-3B and, subsequently, into Northeast Shark River Slough, to control seepage, and to eliminate the barriers to natural flow patterns between Northeast Shark River Slough and West Shark River Slough (see Figure 4-1)
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From page 133... ...
Program Implementation The final piece in implementation of the Mod Waters project is to develop an operating plan for the pumps and gated structures to move water from WCA3A to Northeast Shark River Slough while ensuring the safety of the Tamiami Trail roadbed. The CSOP is an integrated structural and operational plan for two modifications to the C&SF Project: the Mod Waters project and the C-111 (South Dade)
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From page 134... ...
For the Tamiami Trail portion of the Modified Waters project, the major cost escalation occurred when the necessity for increasing the elevation of the road way to protect its integrity was recognized. The early plans for the project simply included additional culvert volume under the existing roadway, at a cost origi nally estimated to be $2.9 million (USACE, 1992)
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From page 135... ...
, Table 6-3. reevaluation of Tamiami Trail alternatives, the Tamiami Trail modifications cost estimate for the recommended plan (alternative 3.2.2a)
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From page 136... ...
. Additional Tamiami Trail modifications will be needed as the CERP pro gresses and the Decomp project moves forward to allow greater water flow vol umes into Everglades National Park.
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From page 137... ...
The general management philosophy of the 1992 plan was to allow more unconstrained water flows into Everglades National Park. As time went on, the project scope and operating targets changed, with adoption of more active control of water flows, larger-scale land purchases, and significant change in the Tamiami Trail configuration.
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From page 138... ...
CERP leaders will need to find ways to move forward with CERP components even when there is a lack of consensus. Leadership Strong leadership remains essential to achieving Everglades restoration goals by overcoming the many potential conflicting interests involved.
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From page 139... ...
Planners recognize that they cannot anticipate all possible outcomes, but it remains to be seen how willing restoration decision makers will be to significantly alter project designs and/or operations once the projects come on line. Sometimes project design changes come at a significant cost, as with the Tamiami Trail, but the changes are essential to attaining the restoration goals.
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From page 140... ...
portion of Tamiami Trail and elevate the road to 8.5 feet to accommodate additional flow into Northeast Shark River Slough, although this is less flow than was originally envisioned. These alterations should also be compatible with further modifica tions needed for Decomp.
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From page 141... ...
CONCLUSIONS AND RECOMMENDATIONS The history of the Mod Waters project is one of the most discouraging stories in Everglades restoration. The project, which would provide crucial first steps toward ecological restoration within Everglades National Park, has been plagued by changes in direction and scope, parochial interests, debilitating litigation, enormous cost escalation due both to inflation and plan modifications, unanticipated engineering constraints (e.g., Tamiami Trail integrity)
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From page 142... ...
Moreover, it should be recognized that moving forward with the 2008 recommended plan increases the urgency to proceed more quickly to imple ment the additional necessary Tamiami Trail modifications through the CERP, or some other mechanism, so that the restoration benefits for Everglades National Park outlined in the WRDA 2007 conference report can be achieved as soon as possible.
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