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Florida Lake Management Society Annual Conference, Naples, Florida, June 4 – 7, 2007

LAKE JOSEPHINE AQUATIC HABITAT ENHANCEMENT: USING THE TOOLS IN THE TOOLBOX

Beacham Furse and Larry Davis Florida Fish & Wildlife Conservation Commission Okeechobee, Florida

Lake Josephine is a 500-hectare natural “transition” lake located in Highlands County. The lake consists of three lake basins ranging from 105 hectares to 255 hectares connected by shallow natural channels at the south end of each basin. Aquatic habitat problems on Lake Josephine have resulted from stabilized water levels and inadequate control of invasive aquatic plants. Prior to 1969, water levels fluctuated more than two feet each year, including frequent flood events, and provided an environment for dynamic littoral communities. Stabilized water levels created by construction of water control structures on Jackson Creek entering the lake and Josephine Creek exiting the lake allowed development and expansion of tussocks and invasive aquatic plants. The project goal for the Lake Josephine Aquatic Habitat Enhancement Project is management of the lake’s aquatic habitat for the long-term benefit of fish and wildlife and the people who utilize those resources.

The primary objective of any FFWCC aquatic habitat enhancement project is to manage invasive aquatic plants and associated organic detrital material to create beneficial and functional aquatic habitat for fish, wildlife, and people as is feasible. To be "feasible", management must be cost effective, provide ecological benefits, be in the best public interest, and have the greatest potential for success as compared to other available methods. Hardship on riparian owners and other lake users must also be minimized to the extent practical and allowable under environmental permit conditions. In this project, we utilized three management strategies: mechanical removal of tussocks and associated organic sediments, management for diverse native aquatic plant communities through natural recolonization or revegetation, and management of future invasive aquatic plant problems through use of herbicides and aquatic harvesting.

Tussock removal was conducted using two water level scenarios: “extreme low

management” (drawdown to 67.50/68.50 ft.

NGVD).

After

consideration

of

currently

NGVD) and “regulated high water” (71.50 ft. available methodologies, two methods were

determined to best meet project objectives:

1.

Aquatic weed harvesters conditions (Phase I)

to

harvest

tussock

in

the

east

basin

under

“regulated

high”

2.

Temporary dams with pumps and earth-moving equipment in the central and west basins to remove tussock and organic detrital sediments under “extreme low management” (drawdown) conditions (Phase II). Installation of temporary dams across the swales between the basins allowed the pump-down of the west and central basins individually to

desired levels.

Session 6B – Page 4

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