The water impounded at Indian Creek Reservoir near Lake Tahoe, California is approximately one-third surface runoff and direct precipitation and two-thirds reclaimed water exported from South Tahoe Public Utility District Plant. Discussed are the results of tests which determined the temporal changes and relationships between water quality characteristics of Indian Creek Reservoir and those of the reclaimed water. Initially the reservoir would not support fish life, but as the reservoir matured, ammonia levels declined to less than 4 mg/l and by 1970 it was an excellent trout fishery. Approximately 70% of the ammonia nitrogen was lost to the atmosphere by nitrification-denitrification. Good biological productivity indicated access to other phosphorus sources, probably runoff. Relative to conductivity and chemical components the water is of good irrigation quality. Various parameters showed that the reservoir responds to more complex factors than those measurable in the reclaimed waste water, raising the question of the effectiveness of tertiary treatment for recreational impoundments.

A prototype package plant incorporating the rotating disc wastewater treatment process was tested on municipal wastewater at the Village of Pewaukee, Wisconsin, to evaluate its treatment capabilities and establish guidelines for operation and testing of a full-scale rotating disc demonstration plant soon to be put into operation at Pewaukee. The package plant included a rotating bucket feed mechanism, ninety-one 1.75 meter diameter discs divided into two stages, and a secondary clarifier with a sludge-removal mechanism. Variables tested included hydraulic loading, rotational disc speed, sludge recycle, and wastewater treatment as it varied with climatic conditions.

The energy budget approach to cooling ponds has been outlined and applied to cooling ponds. Monthly average weather data from 88 stations throughout the U.S. were used to calculate equilibrium temperatures, heat exchange coefficients, and amount of cooling in various sized ponds receiving the effluent from a standard power plant of 1000-mw capacity, both for average and extreme weater conditions. The data for each station is shown on a chart, and the variation of these results across the U S. is depicted by a series of 28 maps of the U.S. with contours connecting equal values of the parameters. The results may also be used to estimate cooling pond performance for other sized power plants. The maps disclose variations across the U.S., on a given date, of up to 55°F in equilibrium temperature, up to 100% difference in heat exchange coefficients, up to 50% difference in heat lost from a given sized pond, and up to 200% difference in the size of a pond necessary to produce an equal cooling effect.

Effects of rainfall runoff from a beef cattle feedlot on the water quality of a small impoundment were determined. Changes in chemical concentration of impounded water and changes in the community structure of aquatic organisms were measured and related to the amount and composition of feedlot runoff received. Water quality changes were also monitored in a nearby reservoir which received no feedlot runoff to serve as a control. Changes in chemical concentration or population structure of organisms were not apparent for discharges of about one-part feedlot runoff to 40 parts receiving water. Runoff discharges for two pumping periods with each contributing one-fourth of the volume of the receiving water were shown to degrade water quality in the impoundment. Several significant chemical and biological changes occurred. The most dramatic reduction in the biological community was the suffocation of about 90% of the game fish in the impoundment.