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54 ''''''.1 .. 1240 HYDROLOGIC AND HUMAN ASPECTS OF THE 1976-77 DROUGHT 1120 48' WASHINGTON Yakimao 46' Columbia Portlando 44" oEugene 42" 1200 OREGON o I o 1160 r-r.---. I I I I I ~ I \ MONT ANA , , I \.. I I EXPLANATION - Region boundary , , \.. " I , , IDAHO Twin Falls I I 1...;_________ NEVADA I 100 I 200 KI LOMETERS I I 100 MILES Figure 20. Pacific Northwest-WRC Region 17. existed in the vicinity of' Goose Lake for a number of years. Lake levels have been high enough since the late 1850's to submerge the ruts. Precipitation and Runoff From 1972 to 1975, precipitation and run- off had been normal to much above normal except in 1973, Runoff for the 1973 water year was among the lowest 25 percent of record, but that year was between two years of runoff well above normal, Precipitation during the 1975-76 season was near normal or above normal, and runoff was above the median value, near 125 percent of normal, Reservoir storage was about average on October 1, 1976. Therefore, the Pacific Northwest Region was not experiencing a drought in 1976. But 1977 was quite another story. Winter precipitation in western Montana was about 50 percent of normal, ranged from 10 to 40 per- cent in Idaho, and from 40 to 60 percent of normal in most of Oregon and Washington. Be- cause temperatures were above normal during the late fall of 1976 and the winter months, precipitation, which was below normal, occur- red as rain and contributed to the runoff rather than occurring as snow and augmenting the snowpack. One example: The storm of January 16-18, 1977 was warm enough to pro- duce rain at high elevations and actually reduced the below normal snow pack in the