A subdivision developer encountered water while digging trenches associated with developing property at Spring Acres Subdivision, Anchorage, Alaska, during the summer of 1975. He reported encountering water at a depth of about 8 feet in June 1975 and also reported a rise in water level to approximately land surface by early August. Neither incident was expected by the developer. The U.S. Geological Survey, in cooperation with the Municipality of Anchorage, had conducted an artificial-recharge experiment approximately 9,000 feet northeast of Spring Acres Subdivision from May 20 through September 19, 1975. Recharge experiments were also conducted in 1971, 1973, and 1974. The proximity of the 1975 recharge experiment to the subdivision caused speculation on the possible connection between the experiment and the water problems encountered by the developer.

The effect of the artificial-recharge experiments on water levels at Spring Acres Subdivision was evaluated by using two digital-computer models constructed to simulate the water-level rises induced by the artificial recharge. The models predicted that the artificial recharge would have caused water levels in the aquifer immediately underlying Spring Acres Subdivision to rise approximately 0.2 foot from May 20 to August 7, 1975. The models also predicted a total rise in ground-water levels of 1.1 feet at this location from July 16, 1973, to August 7, 1975, as a result of the artificial-recharge experiments.

Water-level data collected for auger holes in March 1975 by a consulting firm for the contractor indicated a depth to water of 6 to 7 feet below land surface at Spring Acres Subdivision at this time. Water levels measured in and near Spring Acres Subdivision several years before and after the 1973-75 artificial-recharge experiments showed seasonal rises of 2 to 12.4 feet. A depth to water below land surface of 2.6 feet was measured 600 feet from the subdivision in 1971 and in the subdivision in 1977. Average depth to water in the area was 7.0 feet from early 1976 to September 1979.