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Last updated: January 15, 2013
Everglades Construction Project:
Stormwater Treatment Areas Clean Polluted Runoff Naturally
Susan Jewell, U.S. Fish and Wildlife Sevice
That's when the dirt was turned for one of the first phases the Everglades Construction Project. It was part of the $825 million water quality restoration project that will take six and a half years to build, if all goes well. The problem? Runoff from the Everglades Agricultural Area flows into the Everglades carrying excess nutrients that cause the ecosystem to be thrown off- balance. The solution? Build Stormwater Treatment Areas (STAs), the flow-through filtration marshes that will be operated to augment the natural filtering abilities of marshes. The plan calls for more than 40,000 acres of effective treatment marshes for STAs, a rather sizable chunk of land by anyone's standards.
Many technologies for removing phosphorus, a major runoff pollutant, were analyzed before the five parties settling the 1988 Everglades Water Quality Lawsuit agreed to the STAs. (The parties were Loxahatchee National Wildlife Refuge, Everglades National Park, Army Corps of Engineers, South Florida Water Management District, and Florida Department of Environmental Protection.) The refuge and the park support the concept because it mimics the natural system as much as possible while causing the least disturbance to the environment. Other technologies were eliminated because they created a toxic byproduct, necessitated the construction of large infrastructures, required the addition of chemicals, or removed too much of the necessary components of Everglades water. While many technologies can remove phosphorus, and some even better than Stormwater Treatment Areas, it is critically important to ecologists that the waters discharging from the STAs have the right balance of carbon, silica, calcium, natural bacteria and algae, and a myriad of other components that aquatic invertebrates require - including a little phosphorus. The technology exists to turn raw sewage into distilled water, but the Everglades doesn't need distilled water - it needs marsh water.
Just how much phosphorus in the runoff is too much for the Everglades? It's a $10 million question. That's about how much money is being spent on research and monitoring to determine the answer.
While these research projects are underway, the Miccosukee Tribe, which lives in the Everglades, has taken a different approach to improving water quality on their land. (See Living in the Everglades: The Native Americans.) The tribe applied to the U.S. Environmental Protection Agency to set the limit for total phosphorus at 10 ppb for water entering their land. After reviewing some 300 scientific papers regarding water quality in the Everglades, the EPA concluded that 10 ppb total phosphorus is scientifically defensible. On May 20, 1999, the EPA approved it, thus providing a strong vertebra in the spine of the final state standards that the Florida Department of Environmental Protection must set by 2003.
While the STAs are designed to remove phosphorus down to 50 ppb from the discharge water, scientists hope that other contaminants will also be removed. At the top of the list is mercury, which has shown a somewhat unexplainable but significant presence in the Everglades.
Under the lawsuit settlement and the Everglades Forever Act, landowners in the Everglades Agricultural Area have been required since 1996 to lower the phosphorus in their runoff by 25 percent. These commercial growers have been using a variety of techniques to accomplish this goal, including applying fertilizer efficiently, preventing runoff with dikes, controlling erosion, and altering pumping operations. These efforts have significantly reduced phosphorus loads from the area, exceeding the target requirement and providing relief even before the STAs are built.
The Everglades Construction Project also involves the control of exotic plants and the improvement of hydropatterns - the flow of water over the surface, including the velocity, direction, location, and depth. If only one aspect of a hydropattern is altered, it could significantly affect the ecosystem. Yet all of these aspects, as well as the hydroperiod (duration of inundation), have been altered in the past 50 years in the River of Grass.
U.S. Department of the Interior, U.S. Geological Survey, Center for Coastal Geology|
This page is: http://sofia.usgs.gov/sfrsf/plw/ecp.html
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Last updated: 15 January, 2013 @ 12:44 PM (HSH)
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