Fort Collins, Colorado — home to about 170,000 people and Colorado State University — draws its drinking water from two sources that most cities would love to have: the Cache la Poudre River and Horsetooth Reservoir. Both originate in the Rocky Mountains, flowing through largely undeveloped watersheds before reaching the city’s treatment plants. The water quality is generally excellent. But northern Colorado’s PFAS contamination story, tied primarily to military installations south of the city, has cast a long shadow over the region’s water conversation.
Source Water: Mountains to Taps
Fort Collins Utilities operates two water treatment facilities. The system draws from the Cache la Poudre River — Colorado’s only nationally designated Wild and Scenic River — and from Horsetooth Reservoir, a Bureau of Reclamation facility that stores Colorado-Big Thompson Project water piped from the Western Slope through a tunnel beneath the Continental Divide.
The Poudre River provides excellent raw water quality for much of the year, though spring snowmelt runoff increases turbidity and the river’s water quality varies seasonally. Horsetooth Reservoir, fed by water from Grand Lake and other Western Slope sources, provides a more consistent supply.
Fort Collins’ treatment process includes coagulation, flocculation, sedimentation, granular media filtration, and disinfection. The city uses ozone as a primary disinfectant (rather than chlorine alone), which reduces the formation of chlorinated disinfection byproducts — a real advantage for water quality. Chloramine is used for secondary disinfection in the distribution system.
The system serves about 100,000 service connections and consistently meets or exceeds all EPA drinking water standards. Fort Collins has won awards for its water quality — it’s legitimately good water.
The PFAS Problem: Military Bases and Regional Impact
Here’s where it gets complicated. Fort Collins’ own water supply has tested at relatively low levels for PFAS, but the city exists in a region where PFAS contamination from military installations has become a major environmental and public health issue.
Peterson Space Force Base and the former Buckley Air Force Base (now Buckley Space Force Base), both located in the Colorado Springs and Aurora areas south of Fort Collins, have been significant sources of PFAS contamination from decades of AFFF use. The contamination from these and other military sites has been detected in groundwater and surface water across the Front Range corridor.
Closer to Fort Collins, PFAS contamination linked to firefighting foam use has been investigated at various facilities [NEEDS VERIFICATION]. The Colorado Department of Public Health and Environment (CDPHE) has been conducting statewide PFAS monitoring, and northern Colorado communities have been part of that effort.
What makes PFAS particularly insidious is its mobility. These compounds travel through groundwater systems and surface water, potentially affecting communities far from the original contamination source. For Fort Collins, the question isn’t just what’s in the city’s own wells and surface water — it’s what’s moving through the broader South Platte River basin and the region’s interconnected aquifers.
Growth Pressure and Water Supply
Northern Colorado is booming. Fort Collins, Loveland, Windsor, and Timnath have all experienced rapid population growth over the past two decades, and that growth translates directly into water demand pressure.
Colorado’s water law — the prior appropriation doctrine — means that water rights are “first in time, first in right.” Fort Collins holds senior water rights on the Poudre River, but the river is fully allocated (and some would say over-allocated). During drought years, junior water rights holders are curtailed first, but even senior rights holders feel the pressure of declining streamflows.
Horsetooth Reservoir provides a critical buffer, but the Colorado-Big Thompson Project faces its own supply challenges as Western Slope water availability fluctuates with snowpack and climate patterns. Fort Collins has been investing in water conservation, reclaimed water for irrigation, and supply diversification to manage growth without compromising water quality or reliability.
What the Data Shows
Fort Collins’ annual water quality reports paint a consistently positive picture. Key highlights from recent reports:
- Lead: Well below the EPA action level of 15 ppb at the 90th percentile
- Disinfection byproducts: Lower than many comparable systems, thanks to ozone disinfection
- Nitrate: Low levels, reflecting the mountain source water quality
- PFAS: The city has been testing and has reported results to customers, with levels generally below the EPA’s new 4 ppt MCLs for PFOA and PFOS [NEEDS VERIFICATION]
The Poudre River does face some water quality challenges in its lower reaches, where agricultural return flows, urban stormwater, and wastewater treatment plant discharges add contaminants. But Fort Collins’ intake is upstream of most of these impacts, drawing from the cleaner upper reaches of the river.
What Fort Collins Residents Can Do
Check the annual water quality report. Fort Collins Utilities publishes detailed reports. The data is genuinely encouraging, but it’s worth reviewing, especially as PFAS standards evolve.
If you’re on a well, get it tested. Private wells in northern Colorado may be more vulnerable to PFAS and agricultural contamination than the municipal supply. Contact the Larimer County Health Department for testing guidance.
Conserve water. In a semi-arid region with growing demand, conservation isn’t just an environmental gesture — it’s an infrastructure investment. Fort Collins’ water conservation programs can help reduce your household use and your bill.
Consider filtration for extra assurance. If you want additional protection against PFAS or other trace contaminants, a reverse osmosis system under your kitchen sink provides excellent removal of virtually all contaminants. For whole-house needs, granular activated carbon systems are effective against many organic compounds.
If you’re concerned about your water quality, a certified water treatment professional can test your water and advise on solutions.