Cape Sable Canal Dam Restoration Finally Funded

After decades of overdrainage, or shunting water to the coast instead of letting it flow naturally through the Everglades, the final piece of the Cape Sable restoration puzzle has been funded by the National Coastal Wetland Conservation Grant Program under the U.S. Fish and Wildlife Service. Audubon’s long history of research on Florida Bay and Cape Sable first called attention to these accelerating problems and has been steadily prescribing restoration and enlisting support for it — with steady progress — for more than a decade.

Located at the southwestern tip of the Florida peninsula and within Everglades National Park, Cape Sable has been drained by canals since the 1930s. The 15-foot-wide canals were dug through wetlands to make way for agricultural land and development but were later abandoned. After Cape Sable became part of Everglades National Park in 1947, staff plugged the canals with earthen dams in an effort to keep more freshwater on the land. Unfortunately, over the next several decades persistent anglers illegally digging through the dams as well as hurricane overwash repeatedly breached the plugs.

Without the dams firmly in place, the canals grew in size with each tidal cycle. They expanded up to five times their original width and deepened as more water rushed through — from a mere one to two feet to 11 or 12 feet. This enabled salt water to penetrate freshwater marshes, converting wetlands to open marshes, eroding the peat soil, and allowing mud flats to now partially fill the largest lake in the area, Lake Ingraham. The resulting fragile ecosystem thus became particularly vulnerable to climate change and rising seas. In fact, sea levels in the area have increased an alarming five inches since 2000 alone, harming the coasts and freshwater wetlands.

In 2012, the National Park Service installed dams made of metal, concrete, stone, and earth on the two largest canals. Five years later, when Hurricane Irma hit the peninsula, scientists at Audubon’s Everglades Science Center assessed the impact that the storm had on restored wetlands and compared with other areas still unrestored. Their observations revealed a marked difference, with restored wetlands exhibiting enhanced resilience and less damage. The resulting evidence confirms that these restoration efforts not only restore wildlife habitat, but also offer protection against coastal storm damage.

Another canal, named for the Raulerson Brothers who once attempted to farm there, also breached. Though temporarily plugged with sandbags on numerous occasions, these efforts ultimately failed and severe erosion continued. Measurements in December 2021 showed that the canal increased to more than 70 feet wide and 11 feet deep. Now, a collaborative effort led by Audubon Florida’s Everglades Science Center, National Audubon Society, the National Park Service, and Ducks Unlimited, with the involvement of federal and state wildlife agencies and past involvement from the Everglades Foundation, will finally plug the Raulerson Brothers canal. Achieving this milestone will protect against hurricanes by restoring critical marshes and the natural flow of water in the area. Without the completion of remaining restoration efforts like this one, unrestrained tidal exchange will continue to cause erosion and salinization of freshwater wetlands, adversely impacting wildlife and submerged aquatic vegetation in many ways.

Audubon Florida has provided scientific data and monitoring to support this project, while Ducks Unlimited is managing the project construction. The project is estimated to cost between $5 and $7 million and is scheduled to begin in 2023. After a decade of Audubon science and advocacy on this issue, we look forward to finally celebrating the benefits to habitat and wildlife that will result from its completion.

*Article published in the Spring edition of State of the Everglades publication.

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