Did You Know? La Paz County Water Facts
The primary source of water in La Paz County is surface water (87%), with groundwater making up the remaining supply (13%). Most surface water in La Paz County comes from the Colorado River and its tributaries. Colorado River water is managed by the US Bureau of Reclamation and the Arizona Department of Water Resources (ADWR) based on Colorado River entitlements. Each entitlement holder manages their own Colorado River water use according to the conditions of their entitlement. Most local groundwater in La Paz County is so-called "fossil water" that percolated into the ground many thousands of years ago and is considered nonrenewable because it is not replenished by nature on human time scales.
Groundwater use is regulated by ADWR within Active Management Areas (AMAs). La Paz County is not located within an AMA, so most groundwater use regulations do not apply there. However, ADWR recently held an informal public meeting on October 15, 2025, to present information and accept comments and questions on whether to initiate procedures to designate the Ranegras Plain Groundwater Basin as an AMA. A recording of this gathering is posted on the ADWR YouTube channel.
ADWR also administers the Adequate Water Supply Program. An Adequate Water Supply determination requires demonstration that a water supply meets water quality standards and is physically, continuously, and legally available for 100 years. The determination of adequacy or inadequacy must be provided to buyers before subdivided lots can be sold to the public.