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in other years are similar to those of 1971 and 1980. water -level declines from winter to summer exceeded 50 ft during 1976 and 1980 in this well; were between 30 and 50 ft during 1972-74, 1977, and 1979; and were less than 30 ft during 1971, 1975, and 1978. Figure 5 shows that precipitation was below normal during 1972-74, 1976, and 1980, and above normal during 1971, 1975, and 1977 - 79. The relation between pry -ipitation, pumpage, and the magnitude of summer water -level declines is affPc`.ed by other factors such as the timing of below - normal precipitation (winter or summer), customary use of wells ii, the Mount Simon --Hinckley aquifer, and V,-npage elsewhere in the aquifer. The Mount Simon -Hinckley and Prairie du Chien -Jordan aquifers supply most of the ground water pumped in the Twin Cities Metropolitan Area withdrawals have caused water -level declines of about 200 ft in the Mount Simon -Hinckley aquifer and 90 ft in the Prairie du Chien -Jordan aquifer since 1890. In addition to long-term water -level changes, seasonal declines occur owing to increased summer pumpage. Future problems related to lowered water levels may be avoided or reduced by informed management of the resource through a better understanding of the hydrogeology of the Twin Cities Metropolitan Area The present I-eport presents preliminary results from the current "Appraisal of the Ground -Water Rescurces of the Twin Cities Metropolitan Area, Minnesota" study and describes and interprets water levels for 1971tiand 1980 for both the Mount. Simon -Hinckley and Prairie du Chien -Jordan aquifers. The water -level data indicate that the patterns of flow in the Prairie du Chien -Jordan and Mount Simon -Hinckley aquifers differ greatly. Flow in the Prairie du Chien -Jordan aquifer is greatly influenced by the Mississippi, Minnesota, and St. Croix Rivers. In the Prairie du Chien -Jordan aquifer, water flows from water -level highs in central Hennepin, Washington, Scott, and Dakota Counties toward the major streams where it discharge`3. The aquifer supplies large quantities of water to wells in the Twin Cities area (average of 154 Mgal during 1976-79) and natural flow patterns in the aquifer are disrupted as water is diverted toward major pumping centers. However, despite heavy pumping, no large cones of depression have developed in the water -level surface, indicating that the aquifer is Highly transmissive and in good hydraulic connection with the overlying drift and with the major streams. Between 1971 and 1980, water levels in the Prairie du Chien -Jordan aquifer rose or declined as much as 25 ft locally in response to changes in the rate and distribution of pumping and in response to short-term climatic changes. However, water levels changed less than 5 ft in most of the study area and no overall trend in water levels is apparent. This is consistent with water -use data that indicate only small changes in annual pumpage from the Prairie du Chien -,Jordan aquifer between 1970 and 197 9. water levels in the Prairie du Chien -Jordan aquifer generally decline du►.,iy summer because of increased withdrawals for air conditioning, lawn sprinkling, and irrigatio. Water levels declined during 1971 as much as 70 ft in Minneapolis and more than 10 ft in all of east -central. Hennepin and south- eastern Ramsey Counties. Summer water -level declines duriiiq 1980 were less 20