A theoretical energy balance model was used to predict water temperatures in small clear streams which have limited heat transfer due to ground water flow. The model was designed for application to coastal streams in central California to determine reservoir release policies that would improve downstream salmon habitat by altering stream temperatures. The results of the model are predicted to be applicable to small clear streams in moderately calm and humid areas throughout the temperate zone, where the winters are not prolonged, and where there is little ground Hater flow.. It predicts that all turbulently flowing wateracts ,. identically. It initially heats more rapidly than non-turbulent water, but reaches a lower asymptotic limit. The predicted water temperature was linearly related (in approximate descending order of importance) ·to the reciprocal of the square root of the thermal diffusivity of the substrate, the ambient water vapor pressure, the initial water temperature, the albedo of the stream bed, and the daily mean air temperature. It was found to have important curvilinear relationships with the angle of shading, the wind speed, and the depth. It was curvilinearly related to the latitude, but was surprisingly insensitive to it. It was insensitive to the annual mean temperature, and the range of daily air temperatures.