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38 '1'.'" . HYDROLOGIC AND HUMAN ASPECTS OF THE 1976-77 DROUGHT The drought in Kansas was at its worst in 1976. The heavy rains in June 1977 ended the drought in eastern Kansas, and by September 1977 enough rain had fallen that it was con- sidered over in central and western Kansas. Similar conditions were reported in Nebraska where soil moisture was inadequate. The water content of the snowpack in the Rocky Mountains of Colorado on April 1, 1976 was 99 percent of normal, but 1 year later it was only 45 percent of normal for that date. By early May 1977 the remaining snow was only at the higher elevations and represented only 21 percent of the normal water content. Timely rains during the summer of 1977 in eastern Co.lorado provided enough moisture to maintain crops at least at average production. In mid-March 1977 the flow of the Nish- nabotna River above Hamburg, Iowa, about 45 mi south of Omaha, Nebr., was down to 20 per- cent of the median flow for March. The monthly mean flow for April of the Grand River at Gallatin, Mo., 65 mi north of Kansas City, was 13 percent of the median flow. Flow for the first half of June was down to less than 1 percent of normal. April 1977 was the eighth consecutive month that streamflow was in the below normal range in Kansas. Significant precipita- tion, 4 to 6 in., over the western third of Kansas late in April improved the soil moisture conditions and did increase streamflow in north-central Kansas. Soaking rains in early May over most of the region caused very little increase in runoff, and storage in reservoirs remained below normal. The rains did reduce the demand for irrigation water, however. By mid-May, Kanapolis and Tuttle Creek Reservoirs in central Kansas were at or very near their conservation pool levels, but four reservoirs to the west were still well below conservation pool levels. These four were still about 20 n below in July. In June'1977, two streams in the Nebraska panhandle reached new minimum flows in 33 and 39 years of record. The effect of the low snowpack in the Rocky Mountains is reflected in the flow of St. Vrain Creek north of Denver, Colo. Monthly flows from January through July and again in September 1977 were among the lowest 25 percent of 86 years of record. The most significant aspect of this statistic is the length of time, 8 of 9 months, that the flow remained so low. Ground-water Conditions The water table in western Kansas dropped an average of 3.5 ft in 1976 which is greater than the average decline during the previous 10 years. By June 1977, water levels at many sites were at or near record low levels. Nebraska registered about 60 new irriga- tion wells per week in May 1977, and the total reached 2,600 by July 1. Water levels in the Platte River Valley of Nebraska in May 1977 were 1 to 4 ft lower than the year before, but by the end of June water levels were near or slightly above long-term average levels in the central and west-central parts of the State. In eastern Nebraska, water levels remained 1 ft or more below 1976 and 2 ft or more below the long-term average levels. There are only a few areas in Iowa where ground water can be pumped in quantities sufficient for crops. During May in Iowa, ground-wa ter levels declined more rapidly than usual, enough to make people concerned, and by mid-June had reached levels that usually occur in the fall. The heavy withdrawals in western Kansas accelerated the mining of the ground-water resource. Temperatures exceeding 1000F and strong winds made irrigation imperative and increased the demand on a stressed resource. Similar weather conditions in Nebraska brought the same result. Water Quality Early in May 1977 concentrations of dis- solved solids and of chloride in the Smoky Hill River at Enterprise in east-central Kansas el\ceeded 1,300 mg/L and 400 mg/L, respec- tively. The maximum chloride concentration recommended for drinking water; 250 mg/L, was almost reached in the Kansas River, but timely rains and increased releases from sto- rage reduced the concentrations to acceptable levels. The first significant runoff in streams that had been dry or virtually dry carried heavy concentrations of dissolved solids and organic materials. This effect was localized, and the overall effect on water quality was minimal.