Flow of water to Florida Bay hampered by efforts to protect endangered bird

OKEECHOBEE — A very wet start to the wet season, with a named tropical storm before the start of hurricane season, meant triple the normal rainfall in the month of May for the South Florida Water Management District.

Water Conservation Areas (WCAs) north of the Tamiami Trail are brimming with freshwater — with water levels a foot above their regulation schedules — and about 1,000 cubic feet per second (cfs) — about 646 million gallons per day — is flowing under the Tamiami Trail to Everglades National Park.

The Cape Sable Seaside Sparrow population in the Everglades could be threatened by increasing water levels in their nesting area. Photo courtesy National Park Service.

However, some of the water control structures that could release more water south are closed for environmental reasons.

The S-12a and S-12b water control structures are closed until July 15 to protect the nesting habitat for the Cape Sable Seaside Sparrow, an endangered species. If those structures were open, flow south could be doubled, according to SFWMD.

The current nesting grounds is not the birds’ historic home. The sparrows were first sighted in freshwater and brackish marshes on their namesake Cape Sable in Monroe County. In the 1930s, Cape Sable was the only known breeding area for the sparrows, according to U.S. Fish and Wildlife Service.

The hurricane of 1935 is believed to have changed the habitat on Cape Sable from one dominated by freshwater plants to one dominated by saltwater plants. Reduced freshwater flows due to upstream water management practices and another hurricane in the 1960s are also believed to have contributed to the sparrows’ loss of their original habitat.
In 1967, the sparrows were given federal status as an endangered species. In 1977, they were put on the critical habitat list.

According to “Progress Toward Restoring the Everglades, the Sixth Biennial Review” published in 2016 by National Academies of Sciences, Engineering, and Medicine; Division on Earth and Life Studies; Water Science and Technology Board; Board on Environmental Studies and Toxicology; Committee on Independent Scientific Review of Everglades Restoration Progress,” the area south of the Tamiami Trail was historically much wetter than it is today. The construction of the road from Tampa to Miami created a coast-to-coast berm which disturbed the natural freshwater sheetflow.

When the road was originally constructed, it often flooded and it was customary to close the road during the wet season. However, after the road was built up to accommodate heavier traffic, water levels were artificially regulated to protect the road. As a result, often when the Water Conservation Areas (WCAs) north of the trail are full, no water is released south from Lake Okeechobee, both to protect the road and the East Coast Protection levy.

As a result of the road construction and water management, the area south of the trail began to dry out, changing from wetlands to marl prairie.

Forced out of their original habitat, the sparrows found a new nesting area in the drier area south of the Tamiami Trail.

In 1998 a review of the 1983 Cape Sable Seaside Sparrow Recovery Plan found that the distribution of the sparrow was restricted to two areas of marl prairies east and west of Shark River Slough, and flanking Taylor Slough.

In 2016, due to the efforts of the U.S. Fish and Wildlife Service (USFWS), a biological opinion was added to on the Corps’ Everglades Restoration Transition Plan (ERTP), which was implemented in 2012 to guide improved management of water flows in the Everglades.

The biological opinion guides the Corps and partners in the Everglades restoration effort in better managing water in ways that improve habitat essential to the Cape Sable seaside sparrow.

Actions called for in the biological opinion include operational modifications to aid in providing suitable nesting habitat for the sparrow. These measures allow the movement of additional water southward under the Tamiami Trail One-Mile Bridge flowing through the Everglades and into Florida Bay in ways that avoid prolonged flooding of the sparrow’s habitat during the nesting season, according to the U.S. Fish and Wildlife Service report.

Prior to Hurricane Andrew in 1992, there were 6,576 sparrows inhabiting Everglades National Park, according to the USFWS website. Hurricane Andrew was followed by several wet years and high discharges of water through water control structures, causing several years of poor conditions for the Cape Sable seaside sparrow. This reduced the sparrow’s ability to recover from the impact of the hurricane and its total population declined to 3,312 in 1993. The Service began consulting with the Corps on the ERTP in 2015.

Due to many factors, including loss of habitat, the sparrow’s population dropped to 2,720 in 2014. As a result of this, in 2016, USFWS developed a revised set of targets to improve the conditions of the Cape Sable seaside sparrow and contribute towards the survival and recovery of the species. Targets include providing at least 90 consecutive dry nesting-season days between March 1 and July 15.

The marl prairie habitat that the Cape Sable seaside sparrow requires persists under a hydrologic regime of 90-210 wet days. If the habitat is dry fewer than 90 days, the grass habitat the sparrow requires often is taken over by woody plants. If the habitat is under water more than 210 days, a wetland habitat emerges, according to the USFWS report
Conservation efforts on behalf of the Cape Sable seaside sparrow include annual range-wide population surveys by ground and helicopter, vegetation and hydrologic monitoring, use of prescribed fire to control woody vegetation, controlling wildfires to protect sparrow habitats, and banding birds so they can be identified in the future.

In June, the South Florida Water Management District appealed the U.S. Department of the Interior to open the S-12A and S-12b water control structures in order to send more water from the Water Conservation Areas (WCAs) north of the Tamiami Trail south, freeing up capacity to flow water from the Stormwater Treatment Areas into the WCAs and thus allowing some water from Lake Okeechobee to flow into the STAs for treatment.

The Miccosukee Tribe has a Federal Reservation and leased lands within the northern portion of WCA 3A. Due to the proximity of the Recommended Plan for the Everglades Agricultural Area Reservoir to these lands, the Tribe expressed concerns over the conversion of the FEB (Flow Equalization Basin) to a deep water storage reservoir south of Lake Okeechobee.

In a letter from the Miccosukee Tribe to the SFWMD dated Jan. 8, 2018, the Miccosukee Tribe asserted that the lack of water flow across Tamiami Trail has caused “discriminatory flooding of Tribal lands.” The Miccosukee Tribe recommends that the de-compartmentalization of the Everglades through construction of CEPP, the opening of the S-12 gates, and the maintenance of culverts on the L-67 and L-29 levees take priority over construction of the Recommended Plan for the Everglades Agricultural Area (EAA) reservoir.

The Cape Sable Seaside Sparrow nests low to the ground. Increasing water levels in the birds’ nesting area could mean extinction. Photo courtesy National Park Service.

Sources for this article include the websites of the U.S. Fish and Wildlife Commission, U.S. Army Corps of Engineers and the South Florida Water Management District.


What’s happening with Cape Sable

Florida Park Service — One of the most drastic landscape changes in Everglades National Park, and one that is complicated by sea-level rise and inland effects, is seen in the Cape Sable area. Cape Sable is a large coastal landmass located at the southwestern tip of Florida that was once characterized by an expansive interior freshwater marsh with associated freshwater lakes. In the early 1900s, settlers, determined to use the area for agriculture, began draining the freshwater out to the ocean so the land could dry.

However, the canals they built — coupled with the effects of hurricanes and the manipulation of water farther north — transformed Cape Sable, and much of this alteration has been aggravated by climate change.

Scientists have used geological clues found in the landscape to estimate historic sea levels long before humans had the instruments to do so. This analysis shows that sea-level rise in south Florida was relatively slow over the past 3,200 years; however, modern instrumentation has recorded an accelerated rate of rise over the past century, which has had visible impacts on Cape Sable.

The canals are now a pathway for salty ocean water and sediments to travel inland, especially during high tides or with the help of strong wind and surge from tropical storms. In recent years, the interior freshwater marsh has disappeared almost entirely, and nearby lakes have filled almost completely with marine sediments.

Changes along Cape Sable also have implications for the mangrove trees that live at the waters edge. In response to rising seas and increased flooding, the trees have been moving inland as the habitat becomes more suitable. And along the coast, high tides and storm surges have helped wash sediments away from their roots and have contributed to erosion along Cape Sable. While many wonder whether coastal plants and mangrove forests will be able to keep pace with sea-level rise, others are beginning to notice similar changes further inland.

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