The Interrelated Conditions of Water Quality and Quantity: An Example From the Lower Illinois River

Tenkiller Ferry is a 5,220 ha reservoir on the Illinois River in eastern Oklahoma that was impounded for flood control and hydroelectric power. Rainbow trout were established as the primary mitigation for the loss of the warm-water fishery in the lower Illinois River. No instream flow standards or water storage have been allocated to support the trout fishery. Unreliable water resulted in an increase in violations of state water-quality standards. Trout stockings were suspended in 2011 for the second time in 60 years as a result of insufficient water quantity and quality. Concern from local anglers and some state and federal legislators coupled with two documented fish kills in 2011 led to the development of two new engineering options and increased inter-agency cooperation in an attempt to prevent future fish kills. Temperature and dissolved-oxygen conditions were collected continuously through the summer months at several locations from the dam downstream approximately 10 km. Flow, dissolved oxygen, and temperature data were used to calibrate a model predicting dissolved oxygen as a function of discharge to recommend a summer minimum flow. Cooperation of agencies to obtain feasible management options will allow continued sustainability of this economically-important fishery.