Effect of temperature on winter runoff

The effect of temperature on the October through March runoff of the Clark Fork River at St. Regis, Montana was examined in a preliminary manner. The runoff potential for each winter season of water years 1930 through 1963, was evaluated and compared to historical records. Temperature records for the October through March period of water years 1931 through 1960 for East Anaconda, Montana were used to develop two simple indices: (1) the minimum monthly mean temperature and (2) the number of consecutive days the maximum daily temperature was 32 deg F or lower. The critical flow of the 1936-37 year resulted from a runoff potential in the lower quartile in combination with the occurrence of record-breaking cold temperatures.