Mount Vernon Water Hardness & Quality Report (2026)

Mount Vernon Public Works Department serves the city of Mount Vernon in Skagit County, Washington, providing drinking water to approximately 35,000 residents across a 12-square-mile service area. The primary source is Judy Reservoir, a 1.45 billion-gallon surface water impoundment located above Clear Lake, supplying residents near Burlington, Mount Vernon, and Sedro-Woolley. Water is treated at the city's filtration plant using conventional processes including coagulation, sedimentation, filtration, and disinfection; no groundwater wells are used for the main supply.

The Skagit River watershed, spanning the North Cascades, feeds Judy Reservoir through upstream tributaries influenced by alpine precipitation and glacial melt. Geology features granitic and volcanic bedrock of the Cascade Range, with Quaternary glacial deposits dominating the reservoir's catchment. These non-carbonate formations — primarily metamorphic rocks and glacial till along with Chuckanut Formation sandstones and siltstones — yield very soft water with low mineralisation, as rainwater percolates quickly without picking up significant calcium or magnesium from limestone or dolomite.

Soft water produces no scale buildup in pipes or appliances, eliminating spots on glassware and reducing soap requirements for excellent lathering. Fixtures like faucets and showerheads require minimal cleaning, and water heaters last longer without mineral insulation. No softener is needed or recommended. The 2023 water quality remains compliant with EPA standards; treatment includes chlorination for disinfection. No violations for lead, copper, or maximum contaminant levels are noted; seasonal turbidity from the reservoir is managed by filtration.