Summary

Description

Cholla Lake is a cooling reservoir for the coal fired Cholla electrical generating plant. The lake provides recreational fishing and water contact recreation. The fish populations are selfsustaining. I collected water, sediment, and whole body fish samples to be analyzed for levels of some possibly toxic inorganic constituents. I also measured dissolved oxygen, pH, and Secchi disk transparency. I compared current fish population structure, fish stomach contents, and the frequency of occurrence of benthos, with those same parameters in previous studies. Water temperature and turbidity have increased; catfish and bluegill have increased in their relative abundance; and the density of benthic invertebrates has decreased. Aquatic insects occur most commonly in the stomach contents of bluegill and filamentous algae in the stomachs of catfish. Selenium levels in all matrices exceed national averages and are above levels in a nearby reservoir unaffected by the power station.