Longview Water Hardness & Quality Report (2026)

Longview, Washington, in Cowlitz County — a major southwest Washington Columbia River community (Longview is one of the largest planned cities in the Pacific Northwest — built from scratch in the 1920s by the Long-Bell Lumber Company as a planned timber and industrial city, designed by George Kessler, a renowned city planner), home of the Port of Longview (a major Columbia River deep-water port — one of the most important grain, potash, and heavy cargo terminals on the US West Coast), an industrial community with major aluminum, paper, and chemical manufacturing, and a diverse Cowlitz County community in the Columbia River–Puget Sound corridor — draws its municipal water supply from the Coweeman River and North Fork Lewis River via the City of Longview Water Division. Water hardness in Longview measures 58.5 mg/L — classified as soft.

Longview's soft supply reflects the southwest Washington Cascade foothills watershed's calcareous-poor volcanic geology. The Coweeman River drains the southwest Washington Cascade foothills (Quaternary calcareous-poor Cascade volcanic alluvium and Eocene Clarno Formation — calcareous-poor volcanic tuff and breccia). The North Fork Lewis River (Lake Merwin) drains the Gifford Pinchot National Forest (Quaternary calcareous-poor Cascade basalt and andesite from Mount St. Helens and Mount Adams watersheds). The calcareous-poor volcanic geology produces the soft 58.5 mg/L.

With hardness at 58.5 mg/L, Longview residents enjoy soft water. City of Longview Water Division consistently delivers water meeting all Washington State DOE and EPA Safe Drinking Water Act requirements.