Mona reviews water-study options: wastewater reuse, new upper zone and policy shift to expand irrigation

Mona City Council held a work session Sept. 9 to review a draft water study from consultant Sunrise that assessed limits on the city’s pressurized irrigation (PI) system and outlined three principal approaches for serving future development.

Sunrise engineer Steven Taylor told the council that “the PI system is at capacity and can't really support additional demand, and it's pressure limited,” adding that pressures drop east of 400 East and that most potential new development lies in that unserviceable area. The firm presented three approaches: a wastewater-reuse booster to feed the existing lower PI zone; creation of a separate upper pressure zone served by the Barnes Well and a new pond; or a policy change that would allow culinary water to be used for outdoor irrigation and be priced/charged accordingly.

Why it matters: Mona’s existing secondary irrigation is run by a private irrigation company and is operated on water shares the company controls. Sunrise said shares are diminishing and the current PI system cannot reliably serve growth east of roughly 400 East because of pressure limits. The city and council members framed the choice as one of cost, complexity and long-term control: city ownership of expanded PI infrastructure would increase municipal responsibilities but could serve growth that the existing system cannot.

Major findings and options

- Capacity and sources: Sunrise presented high-level supply numbers from the study. The presenters said the city shows roughly 476 acre-feet of surplus water rights (mostly in springs), about 387 gallons-per-minute of surplus source capacity (subject to water-right constraints), and storage on the order of magnitude reported in the draft as “about 430,000 gallons” (approximate figure from the draft report). The consultant cautioned the city that “you have this much water right doesn’t mean you have that much wet water.”

- Wastewater reuse to the existing lower PI zone: Sunrise described a concept to pump treated effluent from the wastewater plant into the lower PI system using a booster pump station and chlorination. The firm said state regulators (DEQ) have allowed similar tie-ins elsewhere, though they expect chlorination and public-education measures (signage or purple hose bibs) to be required. Sunrise estimated the rough-order-of-magnitude cost for a booster-and-pipeline reuse installation at just under $1 million (the draft lists a reuse booster/pipe estimate in the ballpark of $919,000). The firm reported current plant flows around 111 gallons per minute and noted the plant’s reuse permit would allow substantially more flow if the city chose to use it.

- Upper pressure zone via Barnes Well and new pond: The study described acquiring and re-equipping the Barnes Well, building a pond (near the old field irrigation pond) at higher elevation, and installing transmission lines and a new PI system for the “pink” upper zone shown in the consultant maps. Sunrise estimated that re-equipping the Barnes Well (to approximately the well’s yield) and building conveyance and pond infrastructure would be a significantly larger undertaking — with substantial excavation, road/utility tie-ins and land purchase — but could serve the higher-elevation development area not reachable by the existing system. Sunrise estimated the Barnes option could serve roughly 190–200 additional connections depending on pump sizing and how the project is phased.

- Policy shift to use culinary water for outdoor irrigation: As an alternative to municipal PI expansion, Sunrise proposed a regulatory/policy option: require new development to bring culinary water rights sufficient for indoor and outdoor uses and allow culinary connections for landscape irrigation rather than requiring a separate irrigation share. That approach would keep the system singular (the city’s culinary system), simplify operations, and create a revenue base (through revised culinary impact fees and/or developer impact fees) that could be used to fund improvements. Sunrise noted the city’s current culinary impact fee is approximately $2,500 and that a separate secondary impact fee does not currently exist because the secondary system is not city-owned.

Funding, grants and rates

Sunrise walked the council through typical funding sources and trade-offs. The consultants said agencies that commonly fund water projects include the state Community Impact Board (CIB), the Division of Drinking Water, the Board of Water Resources and federal programs such as the Bureau of Reclamation’s WaterSMART grants. They said eligibility and grant/loan mixes depend on measures such as MAGI (median adjusted gross income) and other program rules.

The consultants provided an illustrative example: a $1 million project split 50/50 grant/loan at roughly 1% interest over 30 years, amortized across Mona’s roughly 630 equivalent residential connections, would increase rates on the order of $2–$3 per month per customer in the best-case scenario. Sunrise cautioned that eligibility and grant share vary and that high local MAGI can reduce grant eligibility.

Council discussion and next steps

Mayor Kevin Deal repeatedly framed the discussion as a long-term planning decision: “I’m looking 20 years out,” he said, urging council members to keep the study “on the front burner.” Council members and consultants discussed technical constraints (pressure set by pond elevations, interchangeability of “paper” water rights and “wet” water, and local limits on transfers) and legal/regulatory constraints (certain water transfers must be “wet” and local to the PI system). Representatives of Sunrise recommended a phased approach: begin with lower-cost, focused steps (for example, a reuse booster) and move to larger investments (ponds and new transmission) only as development and funding warrant.

No formal action or vote was taken at the session. The council asked Sunrise to finalize the draft with council feedback and return for another work session. Mayor Deal asked staff to circulate the draft reports and invited members to send comments to staff member Sarah Samuelson for consolidation. Sunrise offered to prepare a project package and refined cost estimates if the council indicated a preferred direction.

Ending

Council members did not approve any project during the Sept. 9 work session. The consultants advised that the city could pursue a mix-and-match approach (reuse plus policy adjustments or phased capital works) and that the next steps include internal review, collection of council feedback and a follow-up work session with Sunrise to consider a packaged project and funding plan.