In a normal supply year, more than 90 percent of the city's demand is met with surface water provided by SRP and CAP. In some years, a portion of the supply received from SRP may consist of groundwater pumped from SRP wells to make up for surface water shortfalls. The city also maintains a number of wells for operational flexibility and for use when CAP and/or SRP supplies are reduced.
Water supplies available through both the SRP and CAP systems are based on a wide variety of water rights entitlements, contracts, leases, exchanges and other mechanisms. These supplies are divided into those which can be used only within areas entitled to receive SRP water (i.e. lands within the boundaries of SRP), and all other lands within Phoenix. The distribution of these supplies adheres to the legal and contractual obligations associated with each source, but the city's system provides water to all customers in a seamless manner.
