Casa Grande debates effluent-allocation strategy; council favors prioritizing recharge and a 15–20% reserve
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Summary
City staff presented an effluent-allocation strategy proposing to prioritize recharge until permitted recharge levels are reached, to set an annual recharge reserve of about 15–20%, to separate current effluent volumes from new ADOS-generated volumes, and to use a baseline 50/50 sector split between industrial/commercial and residential.
City staff brought a detailed briefing to the council on an effluent-allocation strategy tied to the new ADOS program and broader water-reuse planning.
Larry, the city staff lead on the topic, framed the issue as balancing public health, conservation, recharge and industrial/commercial needs. “We want to begin to allocate effluent in a manner that will utilize all of the effluent instead of having any excess run down the wash,” Larry said while outlining policy choices and modeling assumptions.
Key figures and current uses: Larry said the 2024 treatment volume was about 6,301 acre-feet and that current allocations were roughly 47% to recharge (long-term storage credits), about 32% to direct deliveries, and about 21% uncommitted. Staff reported a current commitment of 1,370 acre-feet to Copper Mountain Ranch contingent on their construction and on the city’s assured water supply decision order.
Staff proposals and rationale: - Prioritize recharge: Staff recommended prioritizing recharge until the city reaches its permitted recharge threshold at the Santa Cruz Wash (about 3,500 acre-feet at that facility) because long-term storage credits would provide future supply security. - Establish a reserve: Staff proposed setting aside a recharge reserve in the range of 15–20% annually to bank long-term storage credits for future municipal needs; staff said models will be run out to 25% to show impacts. - Separate accounting for ADOS volumes: Staff recommended tracking current effluent volumes separately from new volumes generated under the ADOS program to give better transparency and reporting as development requests increase. - Allocation baseline: As a starting model staff suggested a 50/50 split between industrial/commercial use and residential/long-term storage, with the council retaining authority to adjust allocations on a case-by-case basis.
Council feedback and decisions: Multiple council members voiced support for prioritizing recharge and for creating a reserve to bank credits for future development and municipal uses. Council members also discussed the need to protect the city’s fiscal interests and to avoid over-committing supply for immediate sales.
Next steps: Staff will prepare a draft strategy document with modeling runs and an annual reporting approach and will deliver a draft for council review in the coming weeks, with additional presentation expected for council consideration in March.