FLAGSTAFF — The City of Flagstaff and the Bureau of Reclamation presented a multi-agency value-planning study on Monday that ranks development options for the city’s Red Gap Ranch and other regional water sources and sought direction to develop an appraisal-level scope of work.

Council and water-commission members indicated support to proceed with scoping an appraisal study after presentations from federal and city staff and public questions about costs, water quality, ecological impacts and wildfire vulnerabilities.

The appraisal study would be an early feasibility-level analysis that refines alternatives identified by the weeklong value-planning workshop: (1) develop municipal production wells at Red Gap Ranch with local treatment and optional aquifer storage and recovery (ASR); (2) variants that locate treatment nearer Flagstaff or at intermediate sites such as Twin Arrows; (3) expand nearer-field municipal wells; and (4) import Colorado River water via long-distance conveyance. The value-planning team ranked Red Gap Ranch alternatives highest, with Red Gap plus ASR scoring best in the team’s paired-ranking criteria.

Why it matters

Flagstaff has long-term projections showing a water shortfall under buildout scenarios. Study authors and city staff framed the appraisal work as intended to inform decisions about resiliency and redundancy — particularly after recent wildfire and power-shutdown risks that threaten the city’s existing supplies and its ability to operate local wells.

What the presentation covered

City and federal presenters summarized decades of planning and past investments. The city purchased Red Gap Ranch in 2005 for $7.9 million; the ranch includes about 8,500 deeded acres within roughly 24,000 acres of contiguous holdings and previously developed municipal-size wells. The Arizona Department of Water Resources (ADWR) process previously supported a designation tied to an approximate 16,500 acre-feet figure for the Red Gap aquifer modeling effort.

The Jacobs engineering Phase 2 work provides a 10% design-level cost estimate cited in the presentation; speakers noted that previous briefings cited a project order-of-magnitude near one-half billion dollars. Presenters said the Bureau of Reclamation committed to help develop an appraisal scope and that the city will seek a cost-share agreement for that appraisal.

Energy and treatment

City Sustainability Director Nicole Antonopoulos flagged energy as a central issue: “Energy independence for the Red Gap project is critically important as the project may more than double our city's current energy expenditures,” she said, adding the city’s annual energy costs presently range “between $4 and $6 million a year.”

The Red Gap route involves about 40 miles of pipeline and roughly 2,000 feet of vertical lift from the ranch to Flagstaff, with pumping stations spaced in increments (presenters noted roughly every 500 vertical feet in conceptual designs). Advanced treatment, including reverse osmosis, was treated as likely necessary to meet drinking-water standards for groundwater from Red Gap or for Colorado River imports; presenters said RO treatment is energy intensive and will generate saline reject (brine). The team estimated about 20% of pumped volume might be reject brine under some scenarios.

Options for brine disposal discussed included on-site disposal at the ranch (evaporation ponds), disposal near treatment facilities, or other engineered solutions. Presenters acknowledged local ecological and human-health concerns and said those impacts would be researched further during appraisal-level work.

Partnerships and tribal concerns

The Bureau of Reclamation value-planning effort included Navajo Nation participation and Hopi observers. Presenters and legal counsel referenced the Northeastern Arizona Indian Water Rights Settlement Agreement as the regional legal framework parties are using to shape options and buffering requirements. City and tribal representatives emphasized that groundwater protection and partner acceptability were primary criteria in the study’s weighted scoring.

Public questions and technical clarifications

Speakers and members of the public raised questions about pipeline phasing, the feasibility of scaling treatment and pump stations incrementally, corrosion and piping materials for saline water, potential impacts to local fee-simple well owners, and the long-term hydrogeology of the sea aquifer. John Rasmussen of the Bureau of Reclamation said an appraisal study typically provides comparative “appraisal-level estimates” and that teams “strive” to develop a delivered-cost metric for each alternative to allow relative comparison, though the appraisal-level numbers include wide uncertainty ranges.

Members of the public asked about ecological risks from potential evaporation ponds and the movement of contaminants such as PFAS if advanced-treated wastewater were used in recharge or ASR schemes. Presenters acknowledged those as outstanding study topics to be addressed in appraisal-level scope and subsequent environmental work.

Wildfire and short-term resilience

Presenters stressed wildfire and power-shutdown risk for existing water infrastructure. City staff said approximately three-quarters of the city’s watershed-supplied infrastructure sits on forested lands, and that localized fires can curtail local surface supplies for months to years; they cited an example where upper-basin turbidity issues reduced use of that supply for about two years, removing up to 20% of system supply during those seasons.

Next steps and council direction

Staff and reclamation asked the council and commission for direction to proceed with developing an appraisal study scope, budget and schedule. Sterling Solomon, Flagstaff city attorney, summarized the request as seeking “direction to move forward” and noted that a simple consensus was sufficient.

Council and commission members indicated support with nods and thumbs-up signals; no formal roll-call vote was taken. Presenters said they expect to draft an appraisal scope by the end of the calendar year, brief reclamation management and return with a proposed cost-share and schedule for the formal appraisal phase.

What remains uncertain

Presenters and public commenters said important unknowns remain: detailed delivered-cost estimates at appraisal level (and their precision), final decisions on treatment location and brine disposal, federal and state funding shares, exact timelines for construction if a project is chosen, and the magnitude of any impacts on private wells near the ranch. Presenters said those items are the kinds of technical questions the appraisal study is intended to address.

Public comment highlights

A Navajo speaker offering a blessing said, “We offer blessings to the water because water is holy to us,” framed the discussion in cultural terms and urged consideration of future generations. Public commenters asked for explicit analysis of human- and wildlife-health impacts from brine disposal and of long-term groundwater modeling over multi-decadal horizons.

Outlook

City staff and Reclamation characterized this as a planning step, not a construction decision. The appraisal-level work will aim to convert the value-planning alternatives into a smaller set of appraised options with comparative cost and risk indicators, to let elected officials and regional partners weigh tradeoffs and funding strategies before any commitment to construction.