Reconnaissance of potential for potable ground-water supply at Kipahulu District, Haleakala National Park, Maui, Hawaii

Kipahulu Valley drains an area of 12.7 square miles on the southeast side of the island of Maui, Hawaii. The aquifer underlying the lower reaches of the valley comprises recent lava flows. Fresh groundwater occurs in the aquifer as a thin basal lens, which discharges as diffuse seeps along the shore. Measured basal-water heads were 1.3 and 2.4 feet at respective distances of 600 and 3,500 feet from the shore. Chemical analyses of groundwater samples indicate that the water is potable. Wells to develop the basal water should be located at least 1,000 feet from shore. Well penetration should be limited to the upper half of the basal lens, and drawdown caused by pumping should not be greater than half of the head above sea level in order to avoid the risk of contamination by underlying saline water.