Porcupine Reservoir (Cache) is 4 miles (6.44 km) east southeast of Avon on East Canyon Road. It is on the east fork of the Little Bear River. The name comes from the numerous porcupine found in the area.

Construction on the dam began on July 5, 1961 and was completed in the fall of 1962 at a cost of $533,546.00. Extensive renovations which started in the fall of 1998 were completed in the spring of 1999 at a cost of $5.5 million and brought the dam up to current safety standards. The dam contains 12,800 acre feet of water.

G. William Wiersdorf