Water Quality Division

WQ Priority Watershed Projects

Fort Cobb Lake Watershed Implementation Project 2001-2007

The Fort Cobb Lake watershed covers 314 square miles in southwestern Oklahoma in Caddo, Washita, and Custer Counties. Land use in the watershed is primarily agricultural with wheat, peanuts, sorghum and cotton crops grown in rural communities. Fort Cobb Reservoir and six stream segments in its watershed are listed on the 1998 303(d) List of Impaired Waters as impaired by nutrients, pesticides, siltation, suspended solids, and unknown toxicity. The impairment is thought to be from failing septic systems, runoff from confined animal feeding operations, and agricultural practices that contribute nutrients, silt, phosphorous, pathogens, low dissolved oxygen, and turbidity.

In 2005, the Oklahoma Department of Environmental Quality completed a TMDL for Fort Cobb Reservoir, recommending a 70% decrease in phosphorus from the loading levels documented between 1998 and 2001. Sources of phosphorous included cropland erosion, riparian erosion, septic systems, and livestock waste management. 

Purpose of Project
The purpose of this project is to reduce phosphorous loading to streams and the lake by educating landowners and financially assisting them to implement BMPs that protect riparian areas and reduce nutrients and sediment flowing to streams.To reduce phosphorous, the project provided technical and cost-share assistance to landowners who installed BMPs to reduce soil erosion and phosphorous runoff from their land. The most popular BMP was converting cropland to pastureland by planting Bermuda grass. 

Fort Cobb Lake Watershed Implementation Project 2005-2008

Building upon the success of the 2001 Ft. Cobb/Cobb Creek Reservoir Watershed Implementation Project, this project attempted to convert 35,000 acres of tilled cropland to “no-till” cropland in the Fort Cobb watershed to fulfill the TMDL recommendation that 50%, or approximately 51,000 of the 101,000 acres, of cropland be converted to no-till to achieve phosphorous load reductions. The TMDL completed for the Fort Cobb Reservoir by ODEQ in 2005 was the first based entirely on nonpoint source pollutants. 

Partners

See the Fort Cobb Lake Watershed Project factsheet (pdf) for details        Map  (pdf)