Clackamas County, Oregon: drinking water report. Clackamas County south of Portland has about 421,000 residents in communities including Lake Oswego,
Clackamas County south of Portland has about 421,000 residents in communities including Lake Oswego, Oregon City, and Milwaukie. Water sources include the Clackamas River, Bull Run Watershed, and groundwater. The Clackamas River watershed is relatively well-protected, flowing from the Cascade foothills through a mix of forest and suburban land.
The Clackamas River Water District draws from one of the cleaner rivers in the Portland metro area, but the watershed is not immune to contamination. According to Oregon DEQ's 2024 source water assessment, the river shows seasonal peaks in pesticides from upstream agriculture and forestry operations. Atrazine and 2,4-D have been detected at low levels during spring.
The former Portland Air National Guard Station and other military facilities in the metro area contribute PFAS to the regional groundwater. Oregon DEQ's 2024 PFAS investigation found low-level PFAS in two Clackamas County water systems. A former manufactured gas plant in Oregon City contributed PAH contamination to a localized area that remains under remediation.
Clackamas County's water supply is generally high quality, benefiting from a forested watershed and clean mountain runoff. The main household opportunities are addressing seasonal pesticide traces and providing an additional buffer against emerging contaminants.
Check your water for data at your location. A carbon filter handles seasonal pesticide traces and chlorine taste. For PFAS, reverse osmosis adds targeted protection. Our water filter guide covers both approaches. Get your detailed report for seasonal patterns, and visit our Oregon page for statewide data.