The City of Missoula Public Works & Mobility Department has updated its Water and Wastewater Facility Plans to guide investments in the systems that provide clean drinking water, collect wastewater and protect the Clark Fork River. The updated facility plans give the City a 20-year roadmap to replace aging infrastructure, reduce water loss, maintain reliable service and prepare for responsible community growth, while ensuring Missoula’s drinking water remains safe and local water quality is protected.
Planning today for reliable service tomorrow
Missoula last completed Water and Wastewater Facilities Plans in 2019. The new plans account for infrastructure condition, projected growth and anticipated regulatory requirements. They also help the City prioritize capital projects and understand future costs.
The plans assume approximately 1.64% annual population growth within the existing utility service area, from about 79,500 people in 2024 to about 110,000 in 2044. These updates allow the City to plan ahead, invest strategically and maintain the reliable water and wastewater services Missoula depends on every day.
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Planning ahead for Missoula water
The updated Water Facilities Plan found that the City has enough overall well capacity to meet projected system needs through 2044. The plan recommends targeted investments to maintain that reliability as Missoula grows.
Key recommendations
- Continue replacing at least 2.5 miles of aging water main each year.
- Upgrade aging pumps and pumphouses.
- Replace obsolete system controls at 83 locations.
- Add water storage in the north reservoir zone.
- Plan an additional well north of the Clark Fork River and evaluate future wells near growing areas.
- Continue reducing water loss across the system.
About 135 miles of Missoula's water mains are more than 50 years old. The City has made significant progress reducing leakage by 30% over the past four years, but aging infrastructure and about 12,000 galvanized customer service lines continue to contribute to water loss.
Investing in wastewater reliability and river protection
The Wastewater Facilities Plan found that Missoula's wastewater collection system has enough overall capacity to serve projected growth through 2044, with only two gravity sewer segments identified as undersized during the planning period.
The plan also identifies aging sewer mains and targeted areas that need rehabilitation. It recommends rehabilitating or replacing about 1.3% of the collection system each year, or approximately 4.3 miles.
At the Resource Recovery Facility, the City continues to meet strict environmental standards. In 2025, the facility achieved 100% permit compliance while removing 99% of solids and 80% of nutrients from wastewater before discharge.
Future investments will address aging equipment, community growth and potential regulatory changes. Priorities include repairing corrosion damage, upgrading treatment equipment, replacing the ultraviolet disinfection system and planning for additional treatment capacity.
The Montana Department of Environmental Quality also plans to update Total Maximum Daily Load (TMDL) for the Clark Fork River, which could affect future nutrient discharge limits. Because future requirements remain uncertain, the City evaluated several potential treatment options rather than committing ratepayer dollars before regulators establish new standards.
