Phosphorus in Lake Okeechobee: Sources, sinks, and strategies

Increased phosphorus loads to Lake Okeechobee, the largest lake in Florida, have resulted in higher total phosphorus concentrations in the sediments and water column of the lake's pelagic region since the mid-1900s. In this chapter, we examine the role of phosphorus (P) in this dynamic and heterogeneous ecosystem. The chapter is subdivided into six sections: (1) lake and watershed description, (2) phosphorus in lake sediments, (3) pelagic-littoral zone interactions, (4) phosphorus content in different pools, (5) modeling lake responses to watershed management of phosphorus, and (6) strategies for reducing phosphorus in the future. Given the large amount of phosphorus stored in the lake's sediments (2.87 x 10(7) kg) and its frequent resuspension, it may take a considerable period of time to measure noticeable reductions in P concentration in the lake's water column. However, the sooner P loads are reduced from sources in the watershed, the sooner recovery may begin. Progress has been made, in cooperation with the farmers and ranchers in the watershed, to reduce loads over the past two decades, but further reductions still are needed. In-lake P removal strategies, such as dredging, do not appear to be viable in Lake Okeechobee; both ecological and economic uncertainties restrict their utility and, at present, we discourage their implementation.