Well Water in Littleton, Colorado

Arapahoe County · Population ~45,000 · Aquifer: Municipal Denver Water surface supply; Denver Basin bedrock wells on the unincorporated fringe

Hardness: Hard in Denver Basin wells; municipal supply treated and monitored

Littleton's Water Comes From Denver Water

Under the 1970 Total Service Agreement (updated by the 2011 Water Service Agreement), Denver Water provides all of Littleton's potable water. Denver Water's supply is 100 percent mountain surface water — snowmelt from the upper South Platte, upper Blue River, Bear Creek, South Boulder Creek, and Ralston Creek, stored in Antero, Eleven Mile Canyon, Cheesman, Dillon, and Gross reservoirs, and treated at the Foothills and Marston plants (both immediately adjacent to Littleton) plus Northwater. The city's own Integrated Water Resources Plan documents no residential well system.

Fringe Wells and the Denver Basin

The Denver Basin bedrock aquifer system — the stacked Dawson, Denver, Arapahoe, and Laramie–Fox Hills formations — directly underlies Littleton. The city itself holds decreed rights to pump from the Denver, Arapahoe, and Laramie–Fox Hills aquifers beneath about 7,500 acres within its 1985 boundaries. South of the city, in the Chatfield area of Douglas County, private wells commonly tap the Dawson, Denver, and Arapahoe aquifers. Douglas County has roughly 21,000 residents on individual wells, and the Rural Water Foundation of Douglas County represents about 25,000 rural residents dependent on more than 8,000 active Denver Basin wells.

The squeeze on those wells is real and local: the Chatfield Acres and Chatfield East subdivisions (Littleton-address areas in Douglas County) ran their individual Denver Basin wells dry, forcing an intergovernmental agreement, built around 2014–2016, that piped municipal water to roughly 251 homes.

Well-Water Quality Concerns

The Denver Basin's sediments and rocks are natural sources of selenium, uranium, and arsenic. USGS sampling (SIR 2014-5051, 2003–05) found that exceedances of drinking-water benchmarks for nitrate, selenium, uranium, and arsenic were most frequent in the shallow water-table wells, while in the deeper bedrock aquifers those exceedances occurred in 1 percent or fewer of samples, with no uranium exceedances. TDS, sulfate, iron, and manganese — the characteristic deep-bedrock issues — exceeded benchmarks in roughly 10–20 percent of bedrock samples, and hardness is characteristically high.

Radon is most relevant in the crystalline foothills west of Littleton (the Morrison area), not the city's sedimentary basin fill; no Littleton-specific radon data exists. We found no documented private-well PFAS findings specific to Littleton; statewide, CDPHE offers free PFAS testing to private well owners.

Denver Basin Depletion

Littleton sits inside the most heavily pumped bedrock aquifer system in Colorado. USGS Professional Paper 1257 documented water-level declines exceeding 200 feet in a 135-square-mile area of the Arapahoe aquifer southeast of Denver between 1958 and 1978, with more than 500 feet of decline in local areas; the basin is treated as essentially nonrenewable, managed under Colorado's "100-year rule." The Chatfield-area wells going dry is the local evidence of that decline.

What Littleton Residents Should Know

If you're on Denver Water (the city proper): your water meets all federal standards; the action item is whether you have a lead service line (older homes), which Denver Water replaces free through its Lead Reduction Program.

If you're on a private well on the unincorporated fringe (Chatfield/Douglas County, Ken Caryl/Columbine edge): test for selenium, uranium, arsenic, nitrate, bacteria, hardness, and TDS, and watch your well's yield — Denver Basin wells here have a documented history of going dry. See our testing guide.