Lawton Water Hardness & Quality Report (2026)

Lawton, Oklahoma, the Comanche County seat and largest city in southwest Oklahoma, draws its municipal water supply from the City of Lawton Public Utilities Authority, sourcing from two primary reservoirs: Lake Lawtonka (on Medicine Park Creek, impounding runoff from the Wichita Mountains) in Comanche County, and Lake Ellsworth (on East Cache Creek — a Red River tributary) also in Comanche County. Both lakes capture drainage from the Wichita Mountains region. Water hardness measures 78 mg/L — classified as moderately soft, significantly softer than other Oklahoma cities.

Lawton's moderately soft supply reflects the remarkable geology of the Wichita Mountains — one of Oklahoma's most geologically distinctive features. The Wichita Mountains are composed of Cambrian Carlton Rhyolite (volcanic rhyolite — essentially silica-dominated, calcium-free), Proterozoic Meers Quartzite (pure silica quartzite), and Cambrian granophyre (igneous silica-rich intrusive) — ancient volcanic and crystalline rocks fundamentally unlike the surrounding calcareous Permian Red Beds plains. These hard crystalline rocks dissolve extremely slowly and contribute negligible calcium to Lake Lawtonka drainage. The resulting soft supply — amidst the otherwise very hard Oklahoma landscape — is directly attributable to this unique Wichita Mountains island of Precambrian–Cambrian crystalline rock in the southern Great Plains.

With hardness at 78 mg/L, Lawton residents experience minimal scale challenges. Faucet aerators and showerheads develop deposits slowly — bi-monthly cleaning with citric acid solution is sufficient. Dishwashers produce clean glassware. City of Lawton Public Utilities Authority consistently delivers water meeting all Oklahoma DEQ and EPA Safe Drinking Water Act requirements.