Saturday, January 28, 2017

Restoration of Apopka Lake

On Friday we took an all day trip to Apopka Lake, the third largest lake in Florida but that isn't its real claim to fame (or infamy). Lake Apopka was once a world-class bass fishery. However, the lake was named Florida’s most polluted large lake following a century of abuse that began in the 1890s with construction of the Apopka-Beauclair Canal that lowered lake levels by a third. In 1981, an EPA investigation began and the site was decommissioned and designated as a Superfund clean-up site.
Green Heron

In addition, the decline of Lake Apopka can be traced to:
  • The loss of 20,000 acres of wetlands along the lake’s north shore to farming operations beginning in the 1940s
  • Agricultural discharges laden with phosphorus until the late 1990s
  • Treated wastewater discharges from shoreline communities prior to the 1980s
  • Discharges from citrus processing plants prior to the 1980s
The increase in nutrients discharged into the lake led to a chronic algal bloom, and Lake Apopka’s waters turned pea green. The cloudy water prevented sunlight from reaching underwater vegetation critical to fish and wildlife habitat.
Common Ground Dove
 An estimated 676 birds died on former farms at Lake Apopka during late 1998 and early 1999. Most were American white pelicans, wood storks and great blue herons. Organochlorine pesticide (OCPs) residues remaining from agricultural practices were the primary cause of bird deaths. Birds accumulated OCPs by consuming contaminated fish. The St. Johns River Water Management District has conducted research to better understand the accumulation of OCPs through the food chain, from contaminated soil to fish, and from fish to fish-eating birds.
Ring-necked Ducks
The continual settling of dead algae created a thick layer of soupy muck, which also destroyed the habitat necessary for fish and wildlife to thrive. The bass population significantly declined as gizzard shad became the predominant fish species in the lake. Once the bass disappeared, all the fish camps closed.
Lesser and Greater Yellow-legs
 The St. Johns River Water Management District’s Governing Board approved a rule in 2002 limiting the amount of phosphorus that can be discharged into Lake Apopka or its tributaries as a result of new construction in the lake’s watershed. The district has collaborated with local, state and federal agencies to:
  • Purchase agricultural land along the lake’s north shore, reducing the discharge of phosphorus from the farms and providing an opportunity to restore the former marshes to wetlands
  • Operate the marsh flow-way, which removes total phosphorus from Lake Apopka water
  • Harvest gizzard shad, removing phosphorus and nitrogen in fish tissue from the lake
  • Replant six native wetland species of vegetation in the water along the lake’s shoreline, which helps restore fish and wildlife habitat
Snowy Egret
 If  people care and act on that, changes can be made and pollution can be corrected. More than 19,000 acres of farm land has been purchased and converted marsh land. 19 metric tons of total phosphorus has been removed from the water. Gizzard shad had become the dominant species in the lake, but from 1993 through December 2010, more than 58 metric tons of phosphorus and 175 metric tons of nitrogen in fish tissue was removed from the lake. Six native wetland species of vegetation in the water along the lake’s shoreline, which helps restore fish and wildlife habitat. in a few hours we saw 65 species of birds around the lake and marshes. It can be done!

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