Water quality in the Bear River Basin was surveyed from Aug. 27-29, 1974. The survey was done to determine point and non-point source loading, to see if water quality had improved since adoption of the 1958 Enforcement Conference pollution control measures, to determine cause and effect relationships between major waste sources and receiving water quality, and to find out if major waste sources were complying with their NPDES permits. Survey results showed violations of Idaho Water Quality Standards for bacteria, turbidity, and dissolved oxygen. Levels of mercury and Lindane, a chlorinated hydrocarbon pesticide, were significantly higher in the upper reaches of the Bear River than recommended maximum levels. Changes in BOD's and total coliform bacteria were noted, but there was insufficient data available for these standards to evaluate effectiveness of pollution control measures. Nutrient loading was investigated and related to algal productivity, but not all loading sources were located. Other findings included the realization that point sources did not appreciably affect Bear River water quality except in very localized areas.