Florida's freshwater ecosystems protected with WaStop

The problem

Marsh Landing, an elegant residential community in Ponte Vedra Beach, Florida, United States, uniquely integrates natural beauty and luxurious housing through careful land planning. Concern for nature and the environment has always been foremost in the community design of more than 1,000 single-family homes. Building and infrastructure in coastal areas with natural elevations that range a mere 1 to 2 meters above sea level, however, possess challenges for stormwater management systems using ponds and wetlands; Marsh Landing is no exception.

Successfully maintaining a natural environment that contains wetlands and ponds woven into an active, vibrant community requires careful consideration. Nearly 100 inter- connected retention ponds drain into the Intracoastal Waterway and tidal tributaries. These ponds function as an integrated system to protect the community from stormwater flooding and limit the rate of drainage discharge, further protecting downstream property and watershed quality.

Salinity levels must be controlled to ensure that the ponds function as intended. Only a small increase in water salinity can cause a significant loss of biodiversity and alter the ways that the ecosystem functions. At high tide, the Intracoastal Waterway can fill these ponds with brackish water and reduce their intended design storage capacity, thus increasing the chance of community flood damage.

Additionally, salt water harms freshwater ecosystems surrounding these ponds and further shortens the life of reinforced concrete culverts and control structures. Salt water contains magnesium chloride, sulfate ions, and hydrogen carbonation ions that will essentially attack concrete to a certain degree, but what really starts to corrode in a concrete structure is its inner steel sub- structure. Because concrete is a type of porous material, oxygen and humidity can be present where the salt water comes into contact with the film that surrounds the reinforcing steel inside the concrete, initiating the corrosion process of the steel.

In their juvenile stages, fish are least tolerant to salinity, which potentially inhibits the reproduction of existing populations, and salt-averse species may be replaced by salt-tolerant species such as the three- and ten-spined stickleback in highly saline lakes. Macrophyte diversity may also decrease due to difficulties in plant germination, along with the success of a small number of salt-tolerant species.