Denison Water Hardness & Quality Report (2026)

Denison, Texas, in Grayson County on Lake Texoma at the Texas-Oklahoma border — a historic railroad city and the birthplace of President Dwight D. Eisenhower, positioned at the Denison Dam on the Red River — receives its municipal water from the City of Denison Water Utilities, drawing from Lake Texoma — the massive reservoir impounded by the Denison Dam on the Red River at the Texas-Oklahoma state line. Lake Texoma is one of the largest reservoirs in the United States and provides the primary water supply for numerous north Texas and southeastern Oklahoma communities.

The moderately hard 168 mg/L hardness and TDS of 389.7 mg/L reflect Lake Texoma's mixed watershed character. The Red River drains extensively from Oklahoma's Permian Red Bed country — Permian evaporite formations (gypsum, anhydrite, sodium chloride beds) of the Anadarko and Ardmore basins — which would normally produce very hard, high-TDS water. However, Lake Texoma also receives significant input from the Blue River and other tributaries draining the Arbuckle Mountains Paleozoic carbonate and sandstone terrain (somewhat softer), and the dilution effect of the large reservoir volume moderates the extreme Permian Red Bed chemistry. The net result is a moderately hard supply more palatable than the pure Permian Red Bed water would be.

At 168 mg/L, Denison's water is moderately hard — manageable with routine household maintenance for this historic Texas-Oklahoma border city. Scale forms in kettles and appliances over months, the dishwasher benefits from rinse aid, and faucet aerators need periodic cleaning. Quarterly descaling of heating appliances is appropriate. The PFAS level of 6.6 ppt warrants a certified drinking water filter — Lake Texoma's watershed spans the Oklahoma military and industrial corridor, and the Red River basin's extensive agricultural drainage contributes to PFAS loading in the Denison water supply.