Flagstaff lays out 2025 water production plan; emphasizes backup power and infrastructure repairs ahead of fire season

City water-production staff presented the 2025 Water Production Plan on May 15, telling the Water Commission the utility will rely more on groundwater this year, proceed with multiple infrastructure repairs and upgrades, and expand emergency backup power ahead of potential APS Public Safety Power Shutoffs (PSPS) tied to wildfire risk.

Brian Hunsinger, the city’s water production manager, said the system started the spring at about 35% of available Lake Mary surface-water supply and has fallen to roughly 26 percent. "It's not a good year for surface water production," Hunsinger told the commission, and the utility will "rely more heavily on groundwater" including increased output from the Woody Mountain Well Field and Lake Mary groundwater sources.

Why it matters: The combined program of repairs, meter improvements and backup power is intended to protect daily delivery during wildfire-season power interruptions and to preserve limited surface-water resources.

Key projects and status - Upper Lake Mary dam spillway repairs: Hunsinger said the Army-recommended work on concrete spalling is scheduled while lake levels are low; contractors (preconstruction services awarded to PCL) are planning repairs this spring. - Lake Mary Water Treatment Plant sedimentation-basin rehabilitation: Staff described a multi-year design and budget process; prior designs were paused for budget reasons and the project is now in preconstruction with PCL. The work will replace aging flocculation equipment, sludge collectors and concrete infrastructure that staff said had reached roughly twice its design life. - Lake Mary master meter replacement: A previously recommended vault and full‑flanged mag meter will replace a failing insertion mag meter. Hunsinger said the original insertion meter was installed with insufficient velocity and the replacement should improve accuracy and restore automated control logic used by plant pumps. - 27‑inch raw-water pipeline replacement: The pipeline installed in the 1960s has experienced multiple failures and currently leaks overnight; staff plan a design solicitation later this year to evaluate parallel replacement options and whether to abandon the existing pipe in place. - Tank maintenance and paint projects: Several potable and reclaimed tanks (including Buffalo Park and Railroad Springs) will receive exterior painting and inspection; the Buffalo Park tank exterior will also receive a mural from Beautification Arts and Sciences. - Interbasin pipeline restoration: Staff reported continued repairs to the interbasin pipeline damaged in the 2022 pipeline fire; contractor Hunter has completed multiple sites with funding from the Arizona Department of Forestry and Fire Management and expects to finish remaining work by fall.

Backup power and PSPS planning Hunsinger said APS’s Public Safety Power Shutoff policy can de-energize about 75% of the city’s potable supply (Woody Mountain, Lake Mary wellfields and raw water pump station). The city has been installing mobile generators and interconnection infrastructure since 2018 and purchased five trailer-mounted diesel generators (350-kilowatt units) to deploy to critical sites. "We purchased 5 of these 350 kilowatt, trailer mounted diesel powered generators," Hunsinger explained, and the utility is installing permanent connections at the Woody Mountain Well Field so four of those units should power roughly 2.5 million gallons per day from half the well field when needed.

Hunsinger acknowledged cleaner or battery alternatives have been discussed but said supply-chain and capacity constraints make diesel the most reliable emergency source at present. "A solar field would be a massive array," he said, and battery storage sized for a single well would be impractical with current technology and costs.

Operational notes and controls Hunsinger described redundancy and control challenges: the Lake Mary master meter ties groundwater and surface-water inputs to pump controls and SCADA logic, and the plant has operated with manual controls since the meter failed last fall. He stressed the importance of meter replacement to restore automated pump operation. Commissioners asked about chlorine residuals on the west side of town; Hunsinger said wells at Tuthill and the shop well help maintain residuals and that reconfiguring the Tuthill wellhouse to use both Tuthill 1 and 2 could raise available groundwater capacity substantially.

Next steps and timeline Hunsinger said the city expects to proceed with preconstruction work and Guaranteed Maximum Price (GMP) discussions this year for major plant rehabilitation items and to solicit design services for the 27-inch pipe replacement. Other projects are scheduled through fall and into the next construction season.

Ending: Commissioners thanked staff for the detailed update and asked staff to return with progress updates on the master meter project, sedimentation-basin rehabilitation and interbasin pipeline restoration.