Lake Trafford Restoration

Eric G. Flaig

South Florida Water Management District, Ft. Myers, FL

Lake Trafford is the only freshwater lake in southwest Florida. It is the headwaters to the Corkscrew marsh and at high water level during the wet season it drains south through Fakahatchee strand to Southern Golden Gate Estates Critical project area. Lake Trafford has suffered from several fish kills in recent years that have been linked to hypereutrophic conditions in the lake. The lake water exhibits high phosphorus, nitrogen and algae concentrations. The lake has a thick layer of silty sediment that contains high concentrations of nitrogen and phosphorus. The silty sediment consists of a layer of flocculent organic sediment that is up to 1.5 m thick and a layer of soft marl up to 1.2 m thick. The high nutrient concentrations in the sediment maintain high nutrient concentrations in the lake water. The silty sediments also limit the fish spawning and macroinvertebrate food sources for the fish.

Analysis of the sediment indicates that the organic sediment is separated from the marl by a distinct layer of shells and sand that appears to be the original lake bed. Organic C14 dating indicates that the organic sediment is up to 1000 years old while the shell layer is 5000 years old and the marl is 7000 years old.

The Big Cypress Basin of the South Florida Water Management District and the US Army Corps of Engineers have developed a restoration project for the lake that will remove the silty sediment from the lake. This will improve the water quality in the lake by reducing the availability of plant available phosphorus in the sediment and the lake water. Removal of the flocculent sediment will improve habitat for fish.

A watershed management plan is being developed for the Lake Trafford watershed to control nutrient loads in the future. The watershed management plan includes a stormwater management plan for the Immokalee urban area that drains to Lake Trafford. Immokalee currently has a minimal stormwater drainage system and limited water quality treatment facilities. The watershed management plan will be designed to reduce nutrient loads to the lake in the future.

Water quality in the lake has been sampled monthly for the last six years. The nutrient levels indicate the lake is hypereutrophic. However, the dissolved oxygen level remains high and the fishery has been very productive in the last couple of years.

Flaig, Eric, South Florida Water Management District, 2301 McGregor Blvd. Ft. Myers, FL 33901. Phone: 239-338-2929, Fax: 239-338-2936,