Scenario 1 presents a model simulation using constant withdrawal rates (representing the time period from 1990-1997) for the period 1998-2027, and then extended to steady-state. This scenario provides a baseline for comparison of other simulations in which future withdrawals may increase or decrease.

Results of this scenario indicate that simulated hydraulic heads continue to decline and drop below the top of the formation. Through 2027, hydraulic heads decline in the center of cones of depression in areas of El Dorado, Pine Bluff, Magnolia, and Arkansas County, and in areas of Monroe, Louisiana. Results of the steady-state baseline scenario indicate a substantial number of dry cells (simulated hydraulic head in a cell drops below the cell bottom) in northern Lonoke County and a few in south Nevada County, all within the Sparta outcrop/subcrop area. In general, dry cells result from withdrawal rates exceeding available water. Dry cells in the Grand Prairie area could indicate, based on model assumptions and results, that recent increased withdrawals from the Sparta aquifer for irrigation cannot be indefinitely continued. In addition, the cone of depression in the Grand Prairie area expands from 2027 to steady-state toward the northwest as a result of continued withdrawal from the Sparta aquifer for agricultural crop irrigation with dwindling alluvial aquifer supplies (Joseph, 1998b; T.P. Schrader, U.S. Geological Survey, written commun., 2003).