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~'~I1}l)~~ v '~' _, "'"" \.J:J CHRONOLOGY OF THE 1976-77 DROUGHT 31 stssippi River in 1977 were about one-third those in 1976 in the headwaters, about one- fourth near St. Paul, and 30 percent at lock and dam 10 northeast of Iowa City. The flow for the 1977 water year of the Red River of the North at both Grand Forks and Fargo, N. Dak., was the fifth lowest in 73 and 76 years of record and the lowest since 1935 or 1936, respectively. The four lowest flows occurred between 1931 and 1936. The minimum flow of record occurred in 1934 when the flow at Grand Forks, 75 mi north of Fargo, was 49 percent and the flow at Fargo was 27 percent of that in 1977. Changes in storage in 23 reservoirs in the Wisconsin River basin clearly show the effect of the drought. Normally, surplus flows are stored, usually in March and April and again in September and October; and water levels are held high through May, June, and part of July for the benefit of those engaged in water- related recreation activities. Storage usually is reduced in July and August and D'ecember through March primarily because of releases for hydroelectric power generation. The nor- mal pattern occurred through August 1976, but the usual increase in storage in the fall did not materialize. Storage dropped to 21 percent of capacity at the end of October 1976 and to 6 percent of capacity at the end of February_ 1977. During the following months, the in- crease in storage was only about two-thirds of the increases that occurred in 1975 and 1976. Because of the reduced storage, reservoir releases to the Wisconsin River during the summer of 1977 were cut back to half to two- thirds of normal. This change in operation provided almost the normal amount of water in storage by late August 1977, and the following fall increase brought the storage up to 83 percent of capacity by November 13, 1977. Storage in six reservoirs in the headwaters of the Mississippi River decreased about 100,000 acre-ft during August 1976. The sig- nificant fact related to this decrease is that only 17,000 acre-ft was released to augment low flows in the Mississippi River and the rest was lost by evaporation. The Mississippi River flows were the lowest since the 1930's, and regulation by powerplants reduced the flow at St. Paul to a new record low daily discharge of 530 ft :J;s on August 31, 1976. The water level in Coralville Reservoir on the Iowa River north of Iowa City, Iowa was 5 ft below its normal level from November 1976 to February 1977. Because of a forecast of continued below-normal precipitation, a meet- ing of water users was held at which all agreed to temporarily reduce the authorized minimum release from 150 to 100 ft 3/s. The reduced release was in effect from February 14 to March 18, 1977. Similar conditions prevailed in the Des Moines River basin, and the reduction of the authorized release from Red Rock Reservoir from 300 to 200 ft 3/s was approved and was in effect from February 17 to March 17, 1977. Normal releases were resumed because the general rains across the State on March 11, 12 brought temporary relief to the drought areas. Ground-water Conditions Ground-water levels in Illinois were below average in May 1977, and maximum declines ranged from 2 to 11 ft. A few small communi- ties had to obtain water from new sources, and many rural residents had to haul water when their shallow wells went dry or the yield was too low. A census of rural families that hauled water in January 1977 was taken in 49 of the 102 counties in Illinois, and 24,123 such house- holds were found, and their average cost was about $40. Extrapolation to the other 53 counties brings the estimated total cost to more than $1 million. The per capita con- sumption dropped from about 100 to 37 gal/d, a very low rate. Most wells in the glacial drift in northern Wisconsin are shallow and recharge annually is necessary because the storage is limited. The low precipitation did not provide enough re- charge mainly in northern Wisconsin and water supplies dwindled or failed. At least twice the usual number of permits for new irrigation wells was granted in 1976 and almost as many had been granted through May 1977. Even the cranberry bogs were short of water by Decem- ber 1976. Generally, water levels in Wisconsin in unconsolidated formations, and in dolomite, sandstone, and granite, declined less than 3 ft, and lower levels have been recorded pre- viously. Maximum declines in scattered wells were about 10 ft. Though neither the recharge to the aquifers nor the withdrawals from the aquifers are uniform, ground water is not being mined.