Lake Josephine Water Quality Study

Lake Josephine is comprised of three separate lake basins that are connected to each other by channels that run between the south ends of each basin.  Water quality is different in each basin and there are some concerns for this lake that are being addressed through two projects conducted by several government agencies.  The first project is the 'Watershed Assessment,' while the second project involves the removal of dense plant mats called 'tussock' that have formed at the north end of each basin and along the southern edge of the center and west basins, and in the channels that connect the basins.  These projects are necessary partly due to the hydrologic modifications the lake underwent in the 1960's.

Historically, water flowed into the north end of the east basin through a creek flowing out of Little Lake Jackson to the north.  Water flowed out of the south end of the east basin, to Lake Istokpoga, through Josephine Creek.  However, during the 1960's these small creeks were dug into large channels for flood control purposes and water now flows into and out of the lake differently than occurred naturally.  There is a structure at the outflow that holds water in when the lake surface level is below 71.5 feet above sea level and the structure allows the rapid release of water when the lake level rises above 71.5', preventing the flooding of surrounding homes.  As a result of these changes, the water level in Lake Josephine no longer fluctuates to its natural extremes.  Fluctuation in lake levels is important in the control of aquatic plants, since plants that grow near the shore during high water die back when the water level drops during the dry season.  The aquatic plants no longer die back and have now formed dense 'tussock' areas in large portions of each of the three basins. 

Tussock is unhealthy because fish cannot live in it, boats cannot penetrate it and it decreases the surface area and habitat area of a lake.  Tussock has decreased the water surface area at the north end of all three basins, halving the size of the center basin, has all but closed the access channel between basins, and has eliminated lake access to many lakefront property owners at the south end of the central basin in particular.  Plans are currently underway to remove this tussock through a cooperative effort to be conducted by the Florida Fish and Wildlife Conservation Commission, Highlands County and the Southwest Florida Water Management District.  Tussock was mechanically harvested from the east basin early in 2002.  The central and west basins will be treated in future years if funding is approved.  Tussock will probably be removed from these basins by placing 'dams' between the basins and pumping water out to lower the water level so that trucks and heavy equipment can scrape and haul the plant material.

The Lake Josephine Watershed Assessment is a project cooperatively funded by Highlands County and the Southwest Florida Water Management District.  The tasks of this project are described briefly here.  The watershed of Lake Josephine will be mapped - that is, all the land around the lake that slopes down to the lake will be identified because any water falling on this land will affect the lake.  A paleolimnological study has been conducted through the University of Florida to determine what nutrient levels were in the lake before people arrived in the area and before the flow of water was altered.  The location of aquatic plants and tussock have been mapped, as necessary for the tussock removal project described above.  Lake water was sampled monthly from July of 2000 through November of 2001 to determine water quality with respect to a wide variety of parameters not tested for by Lakewatch.  Ground water monitoring wells were established and sampled to determine how water quality constituents move with shallow ground water towards the lake.  A water budget will be developed to compare the amount of water and nutrients entering the lake to the amount of water and nutrients leaving the lake.  Contact Clell Ford at 402-6545 for more information.