World Wetlands Day: The importance of Everglades Stormwater Treatment Areas
By Caroline Buchanan, Soil and Water Sciences graduate student
February 2, 2021, is the 50th celebration of World Wetlands Day. The goal is to raise awareness about the value of wetlands for the planet and all living things that rely on this diverse ecosystem. Florida is home to many wetlands. According to the U.S. Geological Survey, before development started, half the state was classified as wetlands. The prime example of wetlands in the United States, and a wetland of international significance, is the Florida Everglades.
Historically, the Florida Everglades covered roughly 3 million acres. It connected waterbodies through central and south Florida. As the state began draining the Everglades for agriculture and urban development in the 1800s, its size was reduced to the current area south of Lake Okeechobee. These changes in land use, especially the development of the Everglades Agricultural Area (EAA), significantly disrupted the natural flow of water and increased the inflow of nutrients, notably phosphorus (P). Phosphorus, when exported into a low nutrient freshwater system, promotes the growth of algae and non-native plants. This rapidly accelerates eutrophication, which results in oxygen depletion. In the Everglades, this has negatively impacted the entire trophic structure, starting with the vegetative communities. It has subsequently led to the degradation of the overall ecosystem.
There is no place in the world quite like the Everglades. The ecosystem provides drinking water for Floridians, promotes tourism in the state, provides flood control for south Florida and is known for its extraordinary wildlife.
In the mid-1990s, restoration efforts accelerated with the development of Florida’s “Everglades Forever Act.” The plan called for the reduction of P into the Everglades through the establishment of constructed treatment wetlands called Stormwater Treatment Areas (STAs). The STAs are strategically situated with the EAA and Lake Okeechobee to the north and the Everglades Protection Area to the south, acting as a buffer. The STAs are large, constructed treatment wetlands with highly engineered inflow and outflow structures that control water movement. The success of these wetlands in reducing the amount of P exiting them and entering the southern Everglades area hinges on the extent to which the incoming P is retained and transformed into stable long-term forms within the system by both submergent and emergent aquatic vegetation. The STAs have a large effective treatment area of over 57,000 ac2 of the Florida Everglades. They are restored from both historic wetlands and former farmland and have significantly lowered the average P concentration. In Water Year 2019, the average Everglades National Park inflow P concentrations were below 10 parts per billion (ppb), which is the goal set by the Everglades Forever Act.
The development of the STAs has played a major role in what could be considered the most ambitious wetland restoration project in the world and will be an example in the future for other impaired watersheds. Currently, in Dr. Jonathan Judy’s lab, we are working to characterize forms of organic P and complex inorganic P in STA source waters. We hope to understand the differences in the quality of STA source waters and their potential to impact overall performance. This will further improve the understanding of the ecosystem of this valuable wetland.