Boulder County, Colorado: drinking water report. Boulder County sits along Colorado's Front Range with a population of about 330,000.
Boulder County sits along Colorado's Front Range with a population of about 330,000. The City of Boulder sources its water from mountain watersheds – Barker Reservoir, Silver Lake, and the Boulder Creek drainage – while Longmont draws from the St. Vrain watershed and a share of Colorado-Big Thompson Project water. These high-elevation snowmelt sources start clean, but the treatment and distribution systems add their own complexity, and development along the Front Range introduces contaminants that were absent a generation ago.
The Marshall Fire in December 2021, which burned over 1,000 structures in Louisville and Superior, created a water quality crisis that extended well beyond the fire zone. Benzene and other volatile organic compounds from burned homes leached into the Louisville water distribution system at levels exceeding safe drinking water standards. According to the Louisville Water Department, the system required extensive flushing and pipe replacement, and VOC monitoring continued into 2024.
The EPA's UCMR5 data shows PFAS detections at sampling points in Boulder County systems. Rocky Mountain Metropolitan Airport (Broomfield/Jefferson County border) and the former Rocky Flats site are regional PFAS and legacy contamination sources. A 2024 CDPHE report documented PFAS detections in two public water systems in the county.
Boulder County's mountain source water is cleaner at intake than what most counties deal with, but post-fire contamination proved that distribution system integrity matters as much as source quality. If you are in Louisville or Superior, confirm that your service lines have been cleared.
Check your water for current monitoring data in your area. For PFAS or residual VOCs, a reverse osmosis system provides reliable household protection. Our water filter guide details which systems handle fire-related contaminants. Pull your detailed report for trends, and visit our Colorado page for statewide context.