For small communities, wastewater infrastructure is about far more than pipes and permits. It’s about protecting public health, safeguarding local waterways, and doing it in a way that’s financially realistic for residents. This was the challenge facing the City of Moyie Springs (City) in Idaho, and it’s where our civil engineering firm helped transform a regulatory hurdle into a lasting community investment.
From Regulatory Pressure to a Leap Forward
The City’s original wastewater treatment facility, constructed in the 1960s, operated for decades without a formal discharge permit. When the Idaho Department of Environmental Quality (IDEQ) identified the issue, the City faced increasing regulatory pressure and the risk of daily fines if compliance was not achieved.
Keller guided the City through its IDEQ compliance agreement, beginning with a comprehensive Facility Plan update. We evaluated current conditions and future needs by analyzing population growth, projected wastewater flows, and treatment performance. Our team assessed lagoon and mechanical treatment alternatives, along with river and land application disposal options, while working closely with IDEQ to define permit requirements and discharge limits.
Key Project Takeaways
- $6 million project that came in under budget
- Turned a compliance challenge into a long-term community win
- Secured over $5M in grant funding to significantly reduce residential financial burden
- Designed a one-of-a-kind outfall dropping hundreds of feet to the nearby river
- The wastewater system protects water quality today while setting the City up for future success
“The goal wasn’t just regulatory compliance—it was a practical solution the City could operate and afford for decades.” – Zack Wallin, PE
Right-Sizing Treatment for a Small Community
The City also faced a difficult combination of constraints: limited available land—with property adjacent to a lumber mill—and limited operational capacity. Large lagoon systems were not feasible, while highly complex mechanical plants would have placed an unnecessary burden on operators.
Keller recommended and designed a sequencing batch reactor (SBR) system, providing reliable, high-quality treatment within a compact footprint. The SBR approach offered the City an effective balance—meeting stringent discharge requirements while remaining one of the more straightforward mechanical treatment processes to operate and maintain.
Funding that Made the Project Possible
Even the best technical solution can stall without a viable funding strategy. Keller supported the City well beyond engineering design, helping lead public outreach efforts and financial planning. Following public meetings, the City successfully passed a revenue bond, clearing the way for construction.
Keller then helped the City secure more than $5 million in grant funding, significantly reducing the financial burden on residents. With a completed facility plan and approved design in place, the City capitalized on a rare convergence of state and federal infrastructure funding opportunities—turning a regulatory obligation into an affordable, community-supported investment.
“Being ready at the right time allowed Moyie Springs to turn a challenge into a once-in-a-generation funding win.” – Zack Wallin, PE
A Truly Unique Outfall Solution
One of the most distinctive features of the completed project is the wastewater outfall. Unlike most treatment plants, the City facility sits hundreds of feet above the closest surface water body: the nearby river. Maintaining gravity flow was still the preferred solution—but achieving it required creativity.
The discharge pipeline runs underground as far as possible before transitioning to an above-grade system that descends hundreds of feet down a steep cliff face. This custom configuration required careful design, close coordination with the contractor, and detailed construction oversight, resulting in one of the most unique wastewater outfalls in North Idaho—and likely the state.
Delivering Long-Term Value
Now fully constructed and operational, the Moyie Springs Wastewater Treatment Plant provides the City with a modern, permitted system that protects local waterways and public health. The project brings the City into IDEQ compliance, reduces long-term operational risk, and delivers reliable infrastructure designed to serve residents for decades—without placing an unreasonable financial burden on a small rural community.
Discover how Keller can support your next project with thoughtful, proven engineering solutions here.
And to explore our full range of services, visit Our Expertise page.