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Cockroach Bay Aquatic Preserve - Shoreline Alterations

The shorelines of conservation lands in Cockroach Bay Aquatic Preserve are susceptible to erosion for several reasons. For example, the northeast shoreline of Goat Island has been a site of considerable erosion for decades. Spoil material for a proposed development was deposited on the island in the 1950s, and a nearby boat channel produces wakes that erode the spoil from the island onto the submerged land. The constriction of a parallel channel by the old approach to the Goat Island Bridge on the island’s south shore also may contribute to increased scouring of the island’s north shore. Cordgrass planted by volunteers several years ago has reduced the erosion along part of the shore, but additional plantings are needed to complete the project. The marsh grass spreads quickly to stabilize the shoreline which, in turn, traps mangrove seedlings that root and grow to further protect the shore. Tampa Bay Aquatic Preserves (TBAP) will organize additional volunteer planting events to fill the gaps in the Goat Island shoreline.

Other shorelines in the aquatic preserve are under threat of increased erosion as invasive plants compete with mangroves. The Office of Resilience and Coastal Protection and Hillsborough County had an effective partnership that nearly eliminated Brazilian pepper and other invasive exotic plants on the islands in Cockroach Bay Aquatic Preserve. It is very important that TBAP continue to work with the county and the Florida Park Service to remove resprouting plants while invasive populations are still manageable. TBAP will also visit local landowners whose shorelines host invasive non-native plants to discuss possible solutions for removing the invasive plants, and support efforts by the Florida Park Service to remove invasive plants, as program resources allow.

More than a half century ago, a bridge was built from the end of Neptune Road to Goat Island as part of the proposed development of the island. An approach to the bridge was bulkheaded and filled on the island end of the bridge. The approach still blocks about one-third the width of the channel between Goat Island and the mainland. In addition to producing hazardous currents and eddies, this blockage may contribute to the erosion of the mainland, especially during high-flow periods in the river following storms. Nearly 15 years ago, TBAP secured funds to remove the dangerous concrete decking of the bridge to eliminate the imminent danger of a collapse. Although that hazard has been eliminated, upright structures and the filled island bridge approach remain. TBAP will consult with permitting agencies and the land manager about the removal, contractors about logistics and the potential cost, and then hold public meetings with stakeholders to discuss options. TBAP will collaborate with Division of Recreation and Parks because this issue is directly connected to Goat Island. TBAP will also coordinate with Tampa Port Authority because operations would occur on submerged lands owned by Tampa Port Authority. The goal is to remove all manmade structures from Goat Island, and remove and stabilize the bridge approach within 10 years.

Last Modified:
March 13, 2020 - 1:49pm

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