In 1993, the legislature created a groundwater replenishment authority to be operated by CAP throughout its three-county service area. This replenishment is commonly referred to as the Central Arizona Groundwater Replenishment District (CAGRD). In 1999, the legislature expanded CAP's replenishment authorities and responsibilities by passing the Water Sufficiency and Availability Act. The purpose of the CAGRD is to provide a mechanism for landowners and water providers to demonstrate an assured water supply under the new Assured Water Supply Rules which became effective in 1995.

CAGRD is required by law to submit a plan of operation for approval by the Director of the Arizona Department of Water Resources every ten years.  The CAGRD Plan of Operation covers the period from 2015 through 2025 and describes the activities that CAGRD proposes to undertake in the Phoenix, Pinal and Tucson Active Management Areas over the next 100 years to meet its replenishment obligations for existing and new members.