EAA reservoir water to be reserved for environment

Posted 6/12/20

WEST PALM BEACH — An average 375,000 acre-feet of “new water” will flow annually to the Everglades when the Everglades Agricultural Area (EAA) reservoir is complete, according to information …

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EAA reservoir water to be reserved for environment


WEST PALM BEACH — An average 375,000 acre-feet of “new water” will flow annually to the Everglades when the Everglades Agricultural Area (EAA) reservoir is complete, according to information shared at the EAA Reservoir Peer Review session held online on May 29.

Don Medellin, of the South Florida Water Management District, moderated the session. He said the water reservation will ensure new users will not be allocated the water that is reserved for fish and wildlife.

Water reservations do not prevent dry periods from occurring, he explained. A water reservation does not guarantee a particular volume of water per year. During drought periods, SFWMD implements water shortage criteria for all water allocations.

“What we are doing is protecting the new water that is being stored in the reservoir itself,” he explained.

This reservation will not affect existing water users. However, none of this “new water” will be available for new consumptive water use permits, the presentation explained.

Currently on average, more than 700,000 acre-feet of water go to the Everglades. With the EAA reservoir, on average, an additional 370,000 acre-feet of water will flow to the Everglades each year, according to the information presented, which will mean there be an annual flow of more than 1 million acre -feet of water.

SFWMD Water Resources Division Director Lawrence Glenn said the peer review sessions are designed to make sure the science is sound and appropriate for the needs for fish and wildlife.

“Without an approved water reservation for the EAA reservoir, our federal partners are not required to cost-share this facility,” he explained.

The EAA reservoir, which is currently in the design phase by the U.S. Army Corps of Engineers, will be 4 miles long and 5 miles wide. It will pull water from Lake Okeechobee through the Miami Canal and the North New River Canal. Once in the reservoir, water can flow out in three directions that will benefit the Everglades: west into the new EAA reservoir STA (currently under construction); south into STA 3-4; and, east into the Flow Equalization Basin (FEB). Water from the reservoir can also be sent north through S-628 structure back into the Miami Canal.

The new EAA reservoir can store water 22 feet deep, totaling 240,000 acre-feet of water. Water can be periodically released so the reservoir can be refilled. On average, the plan will deliver, on average, an additional 370,000 acre-feet of water to the southern Everglades, according to the presentation.

Sloughs in the Everglades will stay hydrated for a longer period of time, said Mr. Glenn. Fish and apple snail populations will increase, providing food for birds and other wildlife. The alligator population will spread out. The water that collects in holes dug by alligators benefits other species during droughts.

“We have authority to reserve water for protection of fish and wildlife,” said Mr. Medellin. This prevents the use of reserved water by consumptive users.

“Water reservations do not prevent the use of unreserved water or water already allocated to permitted users,” he said. Water reservations do not guarantee any improvement of water quality.

Water reservations are already in place for the Fakahatchee Estuary, Picayune Strand, the North Fork of the St. Lucie River, Nearshore Central Biscayne Bay and the C-43 West Basin Storage Reservoir.

Water reservation rules are documented in Chapter 40E-10 of the Florida Administrative Code.

He said the EAA reservoir water reservation will protect the water specifically for fish and wildlife, and it will increase flows to Water Conservation Area (WCA) 2 and Everglades National Park. This supports the implementation of the Comprehensive Everglades Restoration Plan.

“The purpose of the Central Everglades Planning Project (CEPP) is to improve the quantity, quality, timing and distribution of water flows from Lake Okeechobee to the Central Everglades, Everglades National Park and Florida Bay while maintaining flood control and water supply for existing legal users,” explained Leslye Waugh of the SFWMD Ecosystem Restoration Bureau.

This will be accomplished by redirecting flows from Lake Okeechobee south instead of sending water east to the St. Lucie Canal or west to the Caloosahatchee River when possible during the wet season, she said.

The EAA reservoir is the main storage feature of the project. The CEPP project implementation report was completed in 2014. Congress authorized CEPP in 2016. That plan included the A-2 FEB. In 2017, Florida Senate Bill 10 authorized modifying the A-2 FEB with a deep water reservoir and adding the EAA reservoir STA. In 2018, the post authorization change added the EAA reservoir to CEPP.

On average annually 825,000 acre-feet of water can flow through the EAA reservoir, including water that currently flows through that area plus additional water that will be sent to the reservoir from lake.

Generally, flows will be captured during the wet season and delivered over the dry season, said Ms. Waugh.

She explained the additional flow will have ecological benefits to the Central Everglades including:
• Improve and/or restore vegetative communities and habitat for fish and wildlife;
• Improve natural processes critical for development of peat soils and tree islands;
• Improve slough vegetation depths, resulting in fewer dryouts;
• Provide longer durations between hydroperiods;
• Additional overland flow to Northeast Shark River Slough will improve the timing, distribution and continuity of sheetflow across the Everglades ridge and slough landscape.

Throughout the year, water levels in the reservoir will be going up and down as it receives and releases water, she explained.

Walter Wilcox of the SFWMD Hydrology and Hydraulics Bureau said the CEPP and EAA reservoir hydrological model used has been peer-reviewed twice and is approved for use by the U.S. Army Corps of Engineers. Model inputs include rainfall, evapotranspiration, topography, land cover, peat thickness, aquifer elevation and structures. He said they ran model simulations using data from 1965 through 2005.

He said to run the models, they assume a set of infrastructures for the system and then run simulations based on historical data.

“We basically through the 1965 rainfall through the existing infrastructure and the improved infrastructure and we look to see the expected changes. Are they desirable?” He said the models are just one of the tools used to evaluate the projects.

He said modeling tools are also used for water quality modeling to make sure the water sent to the Everglades meets the phosphorus limits needed for the ecology there.

Mr. Wilcox said the original CERP plan was for a 360,000 acre-feet storage reservoir and did not include an STA. That plan would have sent about 300,000 acre-feet of additional water to the WCAs and the Everglades each year. He said the current plan meets the CERP goal for the project.

He said the reservoir will benefit the lake because during times of drought, they can use the reservoir to meet water needs and keep more water in the lake. It will also benefit the St. Lucie and Caloosahatchee estuaries because when there is capacity in the reservoir, water from the lake can be sent there instead of being released east and west to the estuaries.

The STA was sized to accomplish the desired flow and reduce the phosphorus to the Everglades, he said. A number of other CERP components help restore the flow. “We’re doing things like backfilling canals to create sheet flow,” he explained.

“There is a whole set of additional infrastructure which helps to move the water through this system.” He said the ability to keep the WCAs hydrated, it will reduce the loss of muck soil and the risk of wildfires.

He said even though more water will move into WCA-3, which has experienced problems with high water levels, the changes will reduce the flooding and damage to the tree islands there because the plan also provides a way for the water to flow out of the WCA.

Dong Yoon Lee of the SFWMD Applied Science Bureau said before the water was managed, this landscape continuously drained. Since the water has been controlled, the system experienced increased water levels in some levels and reduced water in some areas.

Mr. Lee said they study how hydrological changes will impact wildlife such as apple snails, ibis and alligators. The modeling shows the additional water flow will result in a moderate improvements in habitat apple snail population and small fish, minor improvements in habitat for crayfish and alligators and no change in habitat for Cape Sable seaside sparrows.

He said the population of the sparrow has declined by about 60% to 90% since 1990 due to extended hydroperiod in the habitat areas of subpopulation A and D and reduced hydroperiods in the areas of subpopulation F and C.

He said increased flow to Shark River Slough will make the river deeper and also expand the shallow areas which will reduce the habitat for the sparrows in some areas, but changes in the overall habitat might increase connectivity between two subpopulation areas which might have a beneficial effect for those subpopulations.

He said the Lake Okeechobee Service Area has existing legal water users who make surface water withdrawals from the Miami Canal and North New River Canal. There are no increases in water allocations expected, he said.

“We also look at protecting the project waters in the reservoir itself including if any wells in areas surrounding the reservoir could take water away from the reservoir by seepage. “We don’t expect increases in allocations,” he continued.

The purpose of the peer review is an unbiased scientific review to ensure the science is solid. The EAA reservoir peer review is voluntary on the part of the SFWMD.

The peer review panel included Dr. Don DeAngelis, a senior scientist with U.S. Geological Survey who has 25 years experience of research in the Everglades, and Dr. Nathan Dorn of Florida Atlantic University.

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