Mona council debates requiring developer-funded water studies, questions pond irrigation for new subdivision

Mona City Council members spent the bulk of their March 10 work session examining how a proposed 12-lot subdivision could strain the city’s culinary water system and infrastructure. Chair said the council did not "want to go that route" of relying on a developer-installed pond for irrigation and raised concerns that allowing culinary water for outdoor use could overtax the system.

Council and staff reviewed technical constraints beneath the freeway where main trunk lines narrow to 10–12 inches and noted that requiring a developer to enlarge that crossing would be costly and legally complicated. Staff recounted prior permit conditions that required developers to upgrade lines for other subdivisions and said those precedents could factor into discussions about who should pay for upgrades.

The council discussed water availability and capacity: staff cited historical spring output of about 240 gallons per minute (gpm), while a Sunrise report mentioned a possible figure of 210 gpm; staff recommended locating the state well log and driller pump tests to confirm actual capacity. Council members also noted the city holds roughly "800 and something" acre-feet of water rights while current use is roughly 300 acre-feet.

Given uncertainties about both supply and pipe sizing, staff and several council members urged requiring a formal water study before final plat approval. "That should be a water study before even submit[ting] their part of the application process," a staff member said; another recommended that a developer be required to pay for modeling (for example, by Sunrise) to verify fire flows and capacity and to fund necessary upgrades if the subdivision’s demand exceeds available capacity.

Members also debated alternatives such as requiring the developer to buy additional water shares, setting a formula tied to lot size (discussion centered around roughly 1 acre-foot per small lot and an estimated 8–9 acre-feet total for the 12-lot project), or adopting xeriscaping requirements. Several councillors noted enforcement limits: metered overage charges may be the only practical sanction if homeowners use culinary water for irrigation contrary to restrictions.

The council discussed legal and timing constraints for changing the code mid-process. Staff referenced the "pending ordinance" doctrine as one possible mechanism: if an ordinance appears on the city minutes, the council may be able to deny a permit on that basis provided the ordinance is adopted within a specified timeframe. Council members asked staff to consult the city attorney about ordinance timing and legal risk before pursuing any changes that would affect the current application.

Next steps recorded during the session included directing staff to: locate and review driller/pump-test logs, request a water-modeling study scope and cost from Sunrise (or equivalent), develop draft code language or thresholds that would trigger a mandatory water study, and produce an impact-fee and infrastructure-cost estimate so the council can consider developer-funded upgrades before final decisions.