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ARIZONA STATE SENATE
Fifty-Seventh Legislature, First Regular Session
groundwater model; stormwater recharge; AMAs
Purpose
Requires the Director of the Arizona Department of Water Resources (ADWR) to adopt rules and annually update the groundwater model for active management areas (AMA) to account for new natural, incidental or artificial stormwater recharge.
Background
The 1980 Groundwater Management Act established AMAs as part of a comprehensive management framework to address groundwater rights and groundwater overdraft. Currently, there are seven AMAs which include Phoenix, Tucson, Pinal, Prescott, Santa Cruz, Douglas and Willcox. An AMA is a geographical area that has been designated as requiring active management of groundwater or, in the case of the Santa Cruz AMA, active management of any water, other than stored water, withdrawn from a well (A.R.S. Title 45, Chapter 2, Article 2).
ADWR uses groundwater flow modeling to simulate past, present and future impacts of water use on aquifers. Groundwater conditions in Arizona are typically evaluated by analytical models, which present a simplistic evaluation of an aquifer and numeric models, which capture an aquifer's complexity. ADWR has developed regional, numeric groundwater models to simulate Arizona's water supply and future demands. Components of the modeled area including pumpage, recharge, evapotranspiration, streamflow and flow. Across model boundaries are simulated within each regional model developed by ADWR (ADWR: Groundwater Modeling Section and ADWR: Modeling Basics).
There is no anticipated fiscal impact to the state General Fund associated with this legislation.
Provisions
1. Requires the Director of ADWR to adopt rules to update ADWR's groundwater modeling for AMAs.
2. Requires the updated adopted rules to account for any natural, incidental or artificial stormwater recharge to the groundwater basin created through the development of new or existing infrastructure.
3. Requires the Director of ADWR to assume that the stormwater recharge generated by the development of new or existing infrastructure will offset a portion of future groundwater use.
4. Requires the Director of ADWR to annually update the groundwater model for AMAs to reflect new natural, incidental or artificial stormwater recharge.
5. Becomes effective on the general effective date.
House Action
NREW 2/11/25 DP 6-4-0-0
3rd Read 2/20/25 32-26-2
Prepared by Senate Research
March 7, 2025
SB/SN/slp