ST. LUCIE COUNTY ARTIFICIAL REEF UPDATE: Turning Dry Detention Areas into Wet Retention Ponds

Dry detention area at Harmony Heights-Paradise Park after heavy rainfall. Photo credit: St. Lucie County Artificial Reef Program.

Water from canals entering the Indian River Lagoon has reduced water quality and essential fish habitat for decades and is likely to continue impacting seagrass beds, oyster reefs, and the water column as human populations on the Treasure Coast increase.  Taylor Creek and the C-25 canal have delivered excess stormwater runoff, along with agricultural nutrients and urban pollutants to the Indian River Lagoon since the late 1950s when the C-25 was completed.  This canal drains water from 116,000 acres to the Indian River Lagoon affecting aquatic animals.

Aquatic animals use gills to accept oxygen from the water much like terrestrial organisms use lungs to accept oxygen from the air. Both dissolved and suspended contaminants in the water may cause respiratory distress in any organism with gills, including fish. Water contaminated with the nutrients ammonia and nitrite is especially harmful to fish. Suspended sediments can also reduce fish health through effects on the gills and have been shown to affect grouper health.

In addition to affecting fish health, suspended sediments also create navigational concerns when they settle on the bottom of the lagoon, preventing boat passage and covering seagrass beds. Dredging in Taylor Creek occurred in 2004 and is scheduled again for 2021 after sediments reduced the channel depths from 14 feet to 7 feet in certain spots.

The St. Lucie County Public Works Department has been working to prevent flooding in neighborhoods adjacent to the C-25 canal and Taylor Creek while improving the quality of stormwater entering these tributaries.  Dry detention areas have been created adjacent to the Harmony Heights and Paradise Park neighborhoods.  The St. Lucie County Artificial Reef Program is currently exploring the possibility of converting these dry detention areas into wet retention ponds.  By doing this the County can reduce nutrients and suspended sediments entering into the Indian River Lagoon and possibly receive additional nutrient removal credits.

Intergovernmental cooperation is needed to convert the dry detention areas to wet retention ponds.  To prevent flooding, engineers from the St. Lucie County Public Works Department must first determine soil percolation rates and rainfall in the area, as well as nutrient concentrations in surface water, using a series of rain gauges, data loggers, and piezometers.  The St. Lucie County Mosquito Control Department will also monitor these areas to ensure that they do not become breeding grounds for mosquitos.

Recent heavy rains have left portions of the dry detention areas with just a few inches of standing water. This is ideal for the propagation of mosquitos and the Mosquito Control Department has already detected multiple species of mosquito larvae in this standing water. If the pond depth can be increased to just a few feet, native fish like mosquitofish (Gambusia affinis) will survive and prevent mosquito larvae from becoming problematic.

There are also many volunteer opportunities involved with this project. Christa Stone, an on-air radio personality with the radio station B-94.7 FM and a volunteer with the Artificial Reef Program, is educating local residents about the possibilities of using ponds for recreational purposes. In addition to potential water quality and fishing, wet retention areas also have the benefit of creating wetland habitat for birds and other forms of ecotourism.

To learn about recreational opportunities at these ponds, contact Christa Stone at (772) 361-3614 or christa@mytcmedia.com.  To inquire into the possibility of donating end-of-day concrete to make artificial reef modules contact Jim Oppenborn, St. Lucie County Coastal Resources Coordinator at oppenbornj@stlucieco.org or (772) 462-1713.

Dry detention area at Harmony Heights-Paradise Park. Photo credit: St. Lucie County Artificial Reef Program.
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