Impoundment Water Quality Changes Caused by Mixing

Mechanical pumping was used to artificially destratify a 2,380-acre-ft lake in northern Kentucky. The pump drew water from the bottom and discharged it at the surface. Analysis of samples taken weekly, from May 14, 1965 to October 29, 1965 throughout the depth of the lake showed the influence of mixing on water quality. A nearby lake of nearly equal volume, sampled similarly, was the control. Results showed a warming and oxygenating of the lower layers of the test lake that resulted in the precipitation of manganese and the oxidation of sulfide. Mixing neither increased the concentration of any nitrogen form, or the total hydrolyzable phosphorus, nor decreased the clarity in the surface. There was no increase in algal densities. Some data on work requirements and efficiencies are also given.