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Collection System

Denver Water is responsible for the collection, storage, quality control and distribution of drinking water to 1.5 million people, which is nearly one-fourth of all Coloradans. Almost all of its water comes from mountain snowmelt, and Denver is the first major user in line to use that water.

Denver Water’s collection system covers about 4,000 square miles, or 2.5 million acres, and extends into more than eight counties, including Park, Grand, Jefferson, Summit, Teller, Douglas, Clear Creek and Gilpin counties. The collection system is divided in two areas, the South and the North System. On average 80% of Denver Water’s supply is from the South System and 20% is from the North System.

The primary water sources in the South System are the upper South Platte, upper Blue, and Bear Creek watersheds. Denver Water owns and operates nine reservoirs in the South System and owns storage in Chatfield Reservoir (the dam is owned and operated by the Army Corps of Engineers). These sources of water are treated through Foothills Treatment Plant or Marston Treatment Plant; both owned and operated by Denver Water.

The primary water sources in the North System are the upper Williams Fork, upper Fraser, South Boulder Creek and Ralston watersheds. Gross Reservoir and Ralston Reservoir are used for storage upstream of two Denver Water treatment plants. Moffat Water Treatment Plant was constructed in the 1930s and is still in operation. The Northwater Treatment Plant is currently under construction and is planned for operation in 2024. 

Denver Water also owns and operates reservoirs to store and release water for exchange and replacement purposes. Water from these reservoirs does not flow to Denver Water water treatment plants. Williams Fork and Wolford Mountain reservoirs are used in this capacity, as well as Denver Water’s gravel pit reservoirs which are part of the Downstream Reservoir Program.

Denver’s drinking water supply comes from mostly forested, high elevation watersheds. To protect these source waters and continue to provide high quality drinking water at an affordable rate, Denver Water’s source water protection programs focus on healthy forests and watersheds through partnerships with stakeholders and landowners.

Reservoir Capacity (acre-feet) Percent of Total Capacity
Dillon 257,304 36.7
Eleven Mile Canyon 97,779 14.0
Williams Fork 96,822 13.8
Cheesman 79,064 11.3
Gross 41,811 6
Chatfield 28,709 4.1
Wolford Mountain (Denver Water's portion) 25,610 3.7
Antero 20,122 2.9
Marston 19,108 2.7
Ralston 10,776 1.5
Strontia Springs 7,864 1.1
Meadow Creek 5,370 0.8
South Complex 3,561 0.5
North Complex (current gravity storage) 3,495 0.5
Long Lakes 1,787 0.3
Platte Canyon 910 0.1
Soda Lakes (Denver Water's portion) 615 0.1
Total 700,707 100