Stormwater Treatment Areas (STAs) are constructed wetlands that remove and store nutrients through plant growth and the accumulation of dead plant material in a layer of peat.;
Florida's Everglades Forever Act mandated and funded construction of STAs.;
Native wetland plants in the Everglades are adapted to low-nutrient conditions.;
Too much of the nutrient phosphorus promotes an overgrowth of plant life and alters the habitat that Florida's native plants and animals need to thrive.;
Phosphorus is a component of fertilizer and it is carried into the Everglades by stormwater runoff from lawns, farms, roadways and other developed areas.;
A decade ago, before STAs were constructed, phosphorus concentrations in Everglades-bound waters averaged 170 parts per billion (ppb). Today, the concentrations in discharges to the Everglades are as low as 12 ppb.;
HOW THEY WORK;
Stormwater Treatment Areas (STAs) remove phosphorus from urban and agricultural runoff water by channeling it through shallow marshes filled with aquatic plants.;
These plants take up or absorb phosphorus from water traveling through, reducing to very low levels the amount of the nutrients reaching the Everglades.;
Plants that help cleanse water in STAs include cattail, bulrush, Southern Naiad and pondweed. Periphyton and microbial communities also help in the treatment.;
STAs are affected by natural conditions such as weather (rainfall, drought, hurricanes), plant growth rates and invasion of undesirable plant species.;
Water quality and condition in the STAs is continually monitored by District scientists. These data are used as basis for operational decisions and management of the STAs.;
Scientists and technicians make approximately 27,000 visits per year to water quality monitoring stations.;
At almost 17,000 acres, STA-3/4 in western Palm Beach County is the largest constructed wetland in the world.;
The State of Florida has invested $1.8 billion in water quality improvements aimed at lowering phosphorus levels.;
The South Florida Water Management District manages six Stormwater Treatment Areas (STAs) in the Everglades Agricultural Area (EAA) that provide approximately 45,000 acres of effective treatment area.;
STA expansions now under way in the Everglades Agricultural Area will bring the total treatment area to 57,000 acres.;
North and east of Lake Okeechobee, STAs are also used to remove phosphorus from water flowing into the lake, St. Lucie estuary and Indian River Lagoon.;
As of April 2012, the Everglades Agricultural Area Best Management Practices and Stormwater Treatment Areas together have removed more than 4,000 metric tons of total phosphorus from water entering the Everglades Protection Area.;
730,000 acre-feet of runoff water were treated through STAs in 2012.;
Treatment, Best Practices and Increased Water Storage
From the sawgrass marshes and tree islands of the Everglades to the mangrove stands along our coastlines and the wetlands, uplands, lakes and river floodplains of the interior, nutrients like phosphorus were once found at very low levels. With decades of residential and agricultural growth, the levels of nutrients and other trace pollutants making their way into these natural areas began to rise. As a result, native ecosystems as well as the plants and animals that are part of those systems began to change. To protect and restore these ecosystems, the South Florida Water Management District is working to remove excess nutrients and other pollutants, or prevent them from entering natural systems.
The Long-Term Plan was developed in response to the 1994 Everglades Forever Act (F.S.373.4592) requirement that the District submit to the Florida Department of Environmental Protection (FDEP) a plan by December 31, 2003, for achieving compliance with the phosphorus, and other state water quality standards in the EPA, and to include the estimated costs, funding mechanisms and implementation schedules associated with the plan. In response to this requirement, the Long-Term Plan for Achieving Water Quality Goals (The Long-Term Plan) was developed.
Stormwater Treatment Areas (STAs) Every plant needs nutrients to survive and thrive, but South Florida's native plants often are out-competed by other plants better able to use heavier nutrient loads. In constructed wetlands known as Stormwater Treatment Areas, some of these non-native plants with an appetite for high levels of nutrients are being used selectively to help remove excess nutrients, so that native plants can once again thrive. more »
Stormwater Treatment Areas, or STAs, are constructed wetlands that remove and store nutrients through plant growth and the accumulation of dead plant material that is slowly converted to a layer of peat soil. Five STAs south of Lake Okeechobee are now removing excess nutrients from agricultural runoff water and, in some cases, runoff from urban tributaries, before discharging it into the Everglades and other natural areas are. Two more STAs north of Lake Okeechobee are now in the planning stage.
STAs are comprised of parcels of land with compartments or cells with different plants predominating in each cell. Emergent plants, like cattails, pickerel weed and bulrush, remove nutrients and store them in peat-like soils as they decay. Submerged plants, including hydrilla, southern naiad and chara, also take phosphorus directly from the water in STAs.
Periphyton, which includes algae or bacteria found on or in the emergent and submerged vegetation, are another very important component of STAs that remove nutrients from the water. Typically, water is moved first through cells with emergent vegetation, then through cells with submergent vegetation. Water moves from one cell or compartment to the next, and at each stage gets cleaner.
Other methods involving chemical treatment were also tested, but proved to be far less effective in removing nutrients from the billions of gallons of water generated by the region's generous yearly rainfall. There are many treatment wetlands all over the country and the world, built at different scales for different purposes. The STAs built to improve the quality of water entering the Everglades system south of Lake Okeechobee are the largest of their kind in the world.
At present, these STAs south of Lake Okeechobee have an effective treatment area of 57,000 acres, which includes STA expansions completed in 2012 in the Everglades Agricultural Area (EAA) that added nearly 12,000 acres of treatment wetlands. North and east of Lake Okeechobee, STAs are also used to remove phosphorus from water flowing into the lake, St. Lucie Estuary and Indian River Lagoon.
As of April 2012, EAA Best Management Practices and Stormwater Treatment Areas together have removed more than 4,000 metric tons of total phosphorus from water entering the Everglades Protection Area. In Water Year 2012, 730,000 acre-feet of water were treated in STAs, reducing phosphorus by 83 percent. More than a decade ago, before STAs were constructed, phosphorus concentrations in Everglades-bound waters averaged 170 parts per billion (ppb). Today, the concentrations in discharges to the Everglades have been as low as 12 ppb.
STA performance data are continually assessed and are reported monthly and yearly. An annual summary of STA performance is also available in the annual South Florida Environmental Report.
As part of the overall effort to decrease excess nutrients flowing into Florida's natural areas, most agricultural operations are now required to adopt Best Management Practices, or BMPs, to ensure that water flowing from agricultural lands is cleaner. BMPs include keeping livestock away from waterways and retaining and cleaning storm water or irrigation water "on-site." BMPs also include reducing the amount of water used for irrigation as well as minimizing fertilizers and pesticides or herbicides used on crops. To date, the combined use of STAs and agricultural BMPs has prevented more than 4,000 metric tons of phosphorus from entering the Everglades.
Urban Best Management Practices
Cities and communities also contribute nutrients and other pollutants to our region's rivers, lakes and wetlands. Storm water flowing over city streets or the rich green lawns and gardens that fill our urban and suburban landscapes can carry excess nutrients from the fertilizers and herbicides we use, as well as all the other contaminants that are a by-product of modern life. more »
Local governments and developers are also required to adopt Stormwater Best Management Practices, or BMPs, that make sure that water flowing into our natural ecosystems is cleaner. These BMPs include keeping direct urban stormwater runoff away from waterways, retaining and cleaning stormwater or irrigation water "on-site" and reducing the amount of water used for irrigation, as well as the type and quantity of fertilizers and pesticides or herbicides used on our landscapes.
Increased Water Storage
Before today's development, much of south and central Florida was land which stored water at least part of the year. Even while that storage has been reduced as the land has been converted for cities and farms, this development also makes it critical at times to quickly remove water from heavy storms or hurricanes to prevent catastrophic flooding. more »
To continue to be able to provide flood protection to people, while preventing excess flows to fragile ecosystems like the Everglades, Lake Okeechobee or coastal estuaries as the price of that flood control, increasing water storage is another key component of water quality protection and ecosystem restoration.
Above-ground impoundments or Water Preserve Areas as well as Aquifer Storage and Recovery pilot projects are now under way to provide additional water storage, so that excess flows are not "lost" to tide, and flows with excess nutrients or pollutants can be kept out of waterways and natural ecosystems. Some examples of plans to increase storage: A 10,500 acre reservoir is planned along the Caloosahatchee River (C-43 West). A reservoir and STA is also planned using approximately 55,000 acres as part of the Indian River Lagoon Project (C-44 Reservoir and STA). In Broward County, a Water Preserve Area (C-9 and C-11 Impoundment) of almost 7,000 acres is planned. In Miami-Dade County, the Biscayne Bay Coastal Wetlands Phase I project will help restore natural water flows to Biscayne Bay and Everglades National Park. And in Palm Beach County, the Fran Reich Preserve (Site 1 Impoundment, 1,600 acres) will collect runoff from the Hillsboro Watershed as well as from the Arthur R. Marshall Loxahatchee National Wildlife Refuge and Lake Okeechobee.