The purpose of this study was to measure the physical, chemical, and biological effects of the thermal discharge from Brandon Generating Station on the Assiniboine River, and to compare the beneficial and detrimental effects of the thermal discharge on downstream water uses. It was found that the thermal discharge has a considerable impact on the thermal regime of the Assiniboine River, preventing the formation of winter ice cover on the river for a variable distance downstream from Brandon Generating Station. This stretch of open water is detrimental in that it prevents the local residents from crossing the river during the winter, but is beneficial in that it allows reaeration to take place, thus increasing the dissolved oxygen concentration of the river water. It appears that the thermal discharge has both beneficial and detrimental effects on the biota of the river, depending on the extent that water temperatures are altered. It was concluded that a final assessment of the relative value of beneficial and detrimental effects could not be made with the amount of data currently available on these effects and with present state of knowledge in resource economics.