McMinnville Water Hardness & Quality Report (2026)

McMinnville, Oregon, the Yamhill County seat — a major northwest Oregon Willamette Valley wine country community (McMinnville is the heart of Oregon's Willamette Valley wine country — directly in the Chehalem Mountains and Dundee Hills wine growing areas, home of the International Pinot Noir Celebration, and considered the wine country capital of Oregon), home of Linfield University (a major Oregon private liberal arts university — Linfield has one of the oldest football programs in the Pacific Northwest and a strong liberal arts tradition), a diverse Yamhill County community with a significant Latino-American and agricultural worker population, and a growing wine tourism and food destination in the Willamette Valley — draws its municipal water supply from the North Yamhill River (Haskins Reservoir) via the City of McMinnville Water and Light. Water hardness in McMinnville measures 85.5 mg/L — classified as moderately soft.

McMinnville's moderate softness reflects the Yamhill County North Yamhill River watershed's calcareous-poor Oregon Coast Range geology. The North Yamhill River watershed at McMinnville–Yamhill County drains: the Eocene Siletz River Volcanics (calcareous-poor basaltic volcanic and intrusive rocks of the Oregon Coast Range — one of the most voluminous oceanic plateau basalt sequences in the western US); and the Quaternary calcareous-poor Willamette Valley alluvium. City of McMinnville treatment produces the moderate 85.5 mg/L.

With hardness at 85.5 mg/L, McMinnville residents enjoy moderately soft water. City of McMinnville Water and Light consistently delivers water meeting all Oregon DEQ and EPA Safe Drinking Water Act requirements.