Declining water levels in part of the Columbia lava plateau, due to pumping, have caused concern for a number of years. Therefore, the U. S. Geological Survey in cooperation with the Washington State Department of Conservation carried out an experiment to determine the feasibility of artificial recharge to halt the decline of water levels in part of the Walla Walla basin, Washington. During the experiment, 71.3 acre-feet (23 million gallons) of surface water was injected into basalt through Walla Walla city well 3 at rates ranging from 630 to 670 gpm (gallons per minute). The chemical and bacteriological quality of the injected water was excellent, and the water contained only 2 ppm (parts per million) of suspended sediment. The injected water probably was nearly saturated with air when it entered the top of the well, and may have entrained some additional air as it fell into the well.