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Such variables as area of water, Ph, conductivity, turbidity, benthic and neustic organisms, plant cover, and disturbance index were recorded in winter from 19 dams. In univariate analysis, area of water, Ph, and a disturbance index differed between dams with and without red-billed teal. When red-billed teal were present, their numbers were correlated with chironomids and Polygonum sp. seeds. For Multivariate Discriminant Function Analyses area of water and disturbance were identified as important variables with turbidity, Ph, and conductivity being of lesser importance. Seven categories of disturbance (human presence, swimming, boating, fishing, shooting, irrigation, watering cattle) and two of attraction (artificial feeding, domestic or pinioned ducks) were established and ranked 0-3 (nil, slight, moderate, extensive). Past disturbance was important and was determined based on experience with use of the dams and the signs of recent human or bovine presence. A disturbance index was calculated as:

Disturbance Index = (total present disturbance - total present attraction) + (total past disturbance - total past attraction).