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Hydrologic data were gathered from the 36.8-sq mi. Joliet Army Ammunition Plant (JAAP) located in Joliet, Illinois. Surface water levels were measured continuously, and ground water levels were measured monthly. The resulting information was entered into database that could be used as part of numerical flow model validation for the site. Deep sandstone aquifers supply much of the water in the JAAP region. This last unit is unconformably overlain by Pleistocene glacial tills and outwash sand and gravel. Ground water levels in the shallow glacial system fluctuate widely. The response to ground water recharge in the underlying Silurian dolomite is slower. In the upland recharge areas, increased ground water levels were observed; in the lowland discharge areas, ground water levels decreased. The decreases are postulated to be a lag effect related to a 1988 drought. These observations show that fluid flow at the JAAP in not a steady-state, either on a monthly or an annual basis. Hydraulic budgets were estimated for the two principal surface water basins at the JAAP site. These basins account for 70% of the facility's total land area. Meteorological data collected at a nearby dam show that the total measured precipitation was 31.45 in. and total calculated evapotranspiration was 23.09 in. for the study period. The change in surface water storage was assumed to be zero for the annual budget for each basin., Original contains color plates: All DTIC reproductions will be in black and white. Includes envelopes with 2 maps.