The Upper Hassayampa groundwater basin covers approximately 787 square miles within Maricopa and Yavapai counties and is located about 60 miles northwest of Phoenix. The basin is characterized by mid-elevation mountains and had an estimated population of 10,479 in 2000. The largest population center is the Town of Wickenburg. Other communities include Congress and Groom Creek. Low-intensity livestock grazing is the predominant land use and most ranches have limited acreages of irrigated pasture to raise additional animal feed. There are no surface water diversions or impoundments besides small stock ponds within the basin. Groundwater is the only source for public water supply, domestic, irrigation and industrial purposes. Public water supply uses the most groundwater in the basin.

The Aravaipa Canyon groundwater basin covers approximately 517 square miles in southeastern Arizona within Graham and Pinal counties. Largely undeveloped, the remote basin has an estimated 135 residents and includes the community of Klondyke. Low-intensity livestock grazing is the predominant land use although there are some irrigated fields and orchards along Aravaipa Creek. Historic mining activity resulted in the creation of the Klondyke Tailings Water Quality Assurance Revolving Fund site in 1998. Groundwater is used for all domestic purposes within the basin as well as most irrigation and stock water supplies. Irrigation uses the most groundwater in the basin.