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32 HYDROLOGIC AND HUMAN ASPECTS OF THE 1976-77 DROUGHT Ground-water levels in two wells in Wis- consin, roughly 50 mi northeast of St. Paul, Minn., had trends somewhat opposite the pre- vailing trends. At one well, new maximum levels in 2t years of record occurred from July 1975 through September 1976, and the water level stayed near the maximum levels through 1977. At the other well, a new maximum level for April was established in 1976, but levels dropped about 6 ft ,between then and Septem- ber 1977 when a new minimum level in a 12- year record occurred. New minimum levels for the month were set for two to four months in 1977 in i three other observation wells in Wisconsin. In western Minnesota about 10 percent of the shallow wells went dry; and though water levels declined in the deep municipal and irri- gation wells, the supply from them was ade- quate. In other parts of the State, the deficient rainfall and low soil moisture caused the farmers to take an intense interest in irrigation and to propose studies related to ground-water supplies. The increased pumping of ground water in Minnesota brought on problems of interference between wells in a few areas. At the index observation well in south- eastern North Dakota, water levels were at record low levels for each month from August 1976 to SePitember 1977 except in April. Water Quality The low flow of the Mississippi River and the configuration of the Minneapolis water system combined to produce water with a mildly unpleasant odor for about 1 week in August 1976. The Minnesota Pollution Control Agency closely monitored the river water for possible adverse conditions that would affect the health of the public. No serious problem developed. On the Mississippi River below the twin cities of Minneapolis and St. Paul, the dissolved-oxygen concentrations are usually low, but zero concentrations were observed by the Metropolitan Waste Control Commission's staff during- the winter of 1976-77. At the Geological. Survey station on the Minnesota River near' Jordan, 30 mi southwest of St. Paul, the dissolved-oxygen concentrations are about 10 mg/L most of the year with a sag to about 7 or 8 mg/L during some winters when ice cover exists. In February 1976, the con- centration dropped to 6.2 mg/L, and values for December 1976, January and February 1977 were 5.9, 2.2, and 5.8 mg/L, respectively. Ice cover was a contributing factor in addition to the low flows which reduced the ability of the river to dilute the waste loading imposed upon it. To put the above values in perspective, among the criteria for dissolved oxygen set by the U.S. Environmental Protection Agency (1976) is a minimum concentration of 5.0 mg/L to, maintain good fish populations. Field and laboratory observations indicate that feeding is diminished or stopped at 3 mg/L and below and that growth is less, even when the low concentration occurs for only part of the day. Activities Resulting from the Drought In Minnesota on lands under State jurisdic- tiem, 3,470 fires burned 144,000 acres in 1976 and 180,000 acres were burned by 1,760 fires in 1977. The increased damage over the average of 1,000 fires and 50,000 acres is at- tributed to the drought. In addition, there were fires in National Forests and Indian reservations. A large part of Minnesota was closed to most outdoor recreation in October 1976 because of the high fire hazard. The most serious fires in Wisconsin oc- curred during the first 5 months of 1977 in- cluding several grass fires and peat fires. To contain one of the peat fires, a large well was drilled and 90 million gallons of water was pumped in about 90 days. Six cities in North Dakota have critical water problems which the drought has aggra- vated, and the drought has shown that 12 other cities have potential problems. Both Minneapolis and St. Paul, Minn., di- vert water from the Mississippi River for their municipal water supply. St. Paul has several lakes that are used to store Mississippi River water and provide reserve supplies, but Minne- apolis has no large storage in its system. In the summer of 1976, the Mississippi River dropped so low that the bottom of the intake for the Minneapolis system was only 5 in. under water. If the river stage had fallen below the intake, a secondary intake could have been used, but the city would have only a 24.-hr supply unless emergency actions were taken. Since then, the city has had a feasi-