Relationship of degree-days above freezing to runoff

Methods of predicting the water supply available at the low-water period in Coeur d’Alene Lake, the storage reservoir for hydro-electric power development on the Spokane River, are assessed. Snow surveys were unsatisfactory because of the low elevation of the drainage area, and the storage rights limiting the retaining of flood waters. Temperature studies indicate that below freezing did not influence runoff, but that temp. above freezing effected snowmelt. The relation between degree days above 32 degF and runoff were computed and plotted against runoff to create a graph for predicting runoff satisfactorily. By using a combination of the summation of degree-days and a summation runoff prior to the date of prediction better results are experienced.A discussion of the paper by Carl Elges and J.E. Church is presented on page 629 (of this same publication).