OUR GEM: Coeur d’Alene’s Wastewater History
By Mike Anderson, City of Coeur d’Alene Wastewater Utility Director
In 1939, the City of Coeur d’Alene began treating its wastewater at a brand-new facility. This plant used secondary treatment, a new level of technology just beginning to be seen in large cities, but almost unheard of in small communities like ours, with a population of barely 10,000.
Motivated by a desire to be a good neighbor and environmental stewards, the City was also curious. How effective could this new process be in protecting our river? The results were remarkable. Instead of removing about 50% of the solids, typical for treatment plants at the time, our secondary process removed up to 95% of solids.
“If Coeur d’Alene votes to correct this condition (polluting the Spokane River with raw sewage) by putting in a disposal plant we will look upon it as a neighborly and just act.” – Highland Park Grange
“One of the finest (treatment plants) in the northwest.” – CDA Press, August 27, 1938
“…will give this city perhaps the most perfect plant in Idaho for the treatment of raw sewage.” – Mike Leonard, Idaho State Chemist, April 1939
Voters passed the bond for our sewage plant by a wide margin, 668 to 160, and by July 31, 1939, the facility was officially in operation.
We were now effectively removing pollution previously discharged to the Spokane River, but that raised a new question. What should we do with all these solids?
In the same forward-thinking spirit that inspired the new treatment process, our community made a decision that still resonates today. We began applying these biosolids to local land. From early on, we recognized these solids as a valuable resource rather than waste. Through anaerobic digestion and drying beds, we transformed what might have been discarded into something beneficial for the environment.
By 1990, Coeur d’Alene formally opened its composting facility, transforming biosolids from a Class B product to a Class A material, safe and beneficial for gardens, landscaping, and community green spaces. This wasn’t simply a response to regulation, it also allowed us to educate the public about the composting process. Today, Coeur d’Green Compost is more than just a byproduct of wastewater treatment. It symbolizes sustainability and is central to our public outreach.
Fast forward to today, and our wastewater system has evolved again. We now operate a tertiary treatment facility using ultra-filtration membranes, removing even more solids and contaminants than ever before. But as our technology advances, so do the complexities of modern life.
When you wash a Teflon pan after a delicious meal, do you ever wonder exactly what’s going down your drain?
One answer is PFAS, short for per- and polyfluoroalkyl substances. Developed in 1938, these chemicals quickly became staples of modern convenience. Teflon pans, Scotchgard, waterproof jackets, cosmetics, and firefighting foam all contained PFAS. Over time, scientists found that certain PFAS compounds, especially PFOA and PFOS, persist in the environment and can accumulate in our bodies. These discoveries led manufacturers to begin phasing them out in the early 2000s.
To assess whether these substances were making their way into our compost, the City conducted tests on Coeur d’Green Compost. The results were reassuring. PFAS levels were extremely low, essentially at or below detection limits.
We now understand that PFAS are not created by wastewater treatment processes but reflect products used in our homes. Rather than vilify biosolids, which are carefully treated and beneficial, we believe the best path forward is source control, reducing PFAS at their origin.
Our community has a proud history of environmental foresight, from building one of the first secondary treatment plants in the region to achieving phosphorus discharge levels among the lowest of any treatment plants worldwide. As we face new challenges like PFAS, we must continue that legacy by staying informed, proactive, and working together to protect this community we call home.
