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<br />110Q <br /> <br />HYDROLOGIC AND HUMAN ASPECTS OF THE 1976-77 DROUGHT <br /> <br />100Q <br /> <br /> <br />34 <br /> <br />__"""'- 'c <br />----------------------~~~ <br /> <br />48' <br /> <br />44' <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />L__ R,wlln. <br /> <br />------- <br /> <br />WYOMING <br /> <br />10SQ <br /> <br />---, <br />----------------- \ <br />f <br />I <br />\ <br />\ <br />\ <br />\ <br />I <br />\ <br />\ <br />----1 <br /><, <br />I <br />I <br /> <br />'?/. <br />" <br /> <br />EXPLANATION <br /> <br />I <br /> <br />___J <br /> <br />-Region boundary <br /> <br />o 100 200 KILOMETERS <br />I I <br />I I <br />o 100MII.ES <br /> <br />Figure 13. Missouri basin-WRC Region 10 (upper part). <br /> <br />Precipitation and Runoff <br /> <br />Precipitation during 1975 was above normal <br />over the region except in the southeast corner <br />of Wyoming and most of southern South Da- <br />kota where precipitation was between 75 and <br />100 percent of normal. <br />The above normal precipitation continued <br />through April 1976 over most of the region <br />though > parts of all four States had below <br />normal precipitaliQn' at one time or another <br />between January and March 1976. May precip- <br />itation was below normal over all the region <br />except for a small, band across southeastern <br />Wyoming. During the summer of 1976 rainfall <br />was generally below normal-as low as 25 <br />percent of normal in the Dakotas in <br />July--€ven though" several localized areas <br />showed much above normal precipitation. <br />During the last. four months of 1976, <br /> <br />precipitation continued to be below normal. In <br />South Dakota, the annual precipitation during <br />197.6 in the western part of the State was <br />about normal, while in the eastern part <br />deficiencies ranged from 6 to 13 in. or about <br />30 to 65 percent of normal. The drought of <br />1976 was considered to be the most severe <br />during the 20th century in much of this region. <br />Monthly precipitation in both January and <br />February 1977 was less than 2 in. over the en- <br />tire region. March precipitation ranged from <br />less than 1 in. in parts of Montana, North <br />Dakota and Wyoming to more than 4 in. in <br />south-central South Dakota. The latter <br />amount was five times normal for March. April <br />1977 precipitation was deficient over most of <br />the region; in fact, in Montana, April 1977 was <br />the second driest April in 98 years of record. <br />Good rains fell in May over the areas that <br />were below normal in April, and rainfall was <br /> <br />~ <br />