7740 - Laserfiche WebLink

Home Browse Search

Water Temperature Water temperature data are not available for the Gunnison River prior to construction of the Aspinall Unit. The only available data were taken with a thermograph near the Uncompahgre Project tunnel in 1964 and 1965 (Kinnear 1967). Wiltzius (1978) used these data to predict that the maximum water temperature change in the tunnel area would be a decrease of 6 to 12 °F during the spring and summer months. Stanford and Ward (1983) documented water temperatures at Crystal Dam (just upstream from the tunnel) in 1979-1980 that were as much as 10 °C lower than those recorded by Kinnear (1967). We used the above information to assume a 'worst case' temperature change below Crystal Dam of -6 °C during March, April, May, and September, and -11 °C during June, July, and August. We added these amounts to recent water temperature data below Crystal Dam to approximate water temperatures that might have occurred prior to construction of the Aspinall Unit. We then estimated changes in mean, bi-monthly water temperature for March through September at two locations in the Gunnison River (river miles 2 and 20) and two locations in the Colorado River (river miles 49 and 136) using the Stream Network Temperature Model (SNTEMP; Theurer et al. 1984). SNTEMP is a mechanistic, one-dimensional heat transport model that predicts the daily mean and maximum water temperature as a function of stream distance and environmental heat input. SNTEMP is applicable to a stream network of any size or order. It includes (1) a solar model to predict the solar radiation that penetrates the water by latitude and time of year, (2) a shade model that predicts the riparian and topographic shading, (3) algorithms that make meteorological corrections used to predict changes in air temperature, relative humidity, and atmospheric pressure by elevations within the 10