Cooley East Reservoir: A beautiful view of Thornton’s water supply

 In Resilient Water Systems, Water Storage, Water Supply
By Josh Redman, Senior Water Resources Administrator

There’s nothing I love more than sluggish traffic on 104th. It gives me a chance to take a scenic, snail-paced cruise past Thornton’s raw water reservoirs. As a Water Resources nerd, I consider it a beautiful view. These reservoirs store the water we use every day! The newest one along this route is Cooley East Reservoir.

An old mine gets a new life as a water storage facility.

Cooley East Reservoir is located near the northeast corner of 104th Avenue and the South Platte River. It’s a former sand and gravel mine that Thornton converted to a water storage facility. This reservoir will store over 2,700 acre-feet of the city’s South Platte water. What is an acre-foot of water? Good question. One acre-foot of water is approximately the same as one football field covered with water one foot deep. Imagine a football field sized swimming pool about a half a mile deep. That’s how much water the Cooley East Reservoir holds—a lot of water!

From storage to treatment to your tap.

How will this water get to Thornton’s water treatment plants? Another great question. Construction crews are building a pump station on the southwest corner of the reservoir. This facility will transfer water to an adjacent reservoir via a pipeline. The pipeline will be several feet below the river bottom, encased in concrete. Water flows from the reservoirs to receive high-tech treatment at either the Wes Brown Water Treatment Plant or the Thornton Water Treatment Plant. Finally, it’s sent through our distribution system to your faucet.

Working to secure our water.

There is plenty of work remaining including boring the pipeline underneath 104th Avenue and the construction of the pump station. The completion of this $8.5 million project is slated for the fall of 2021.

Cooley East Reservoir is a testament to a lot of hard work the city has put in to provide clean, safe, high-quality water for our community—even in times of drought. It’s this kind of thinking ahead that ensures we won’t be left behind.

Without Water Life Would Be Pretty Dry

Learn more about the water-security projects the city of Thornton is doing, and what you can do too, at

Cooley East Reservoir Under Construction

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