ELCO receives treated water from the Soldier Canyon Filter Plant, so named because of its location at the base of the Soldier Canyon Dam. The Soldier Canyon Dam is one of four dams constructed west of Fort Collins by the Bureau of Reclamation in the 1940's to create Horsetooth Reservoir. 

Water in Horsetooth Reservoir originates as snow in the upper reaches of the Colorado River Basin. Snowmelt is collected in reservoirs on the western slope and diverted through a series of tunnels and canals for use in northeastern Colorado.

ELCO Water District, North Weld County Water District and the Fort Collins-Loveland Water District jointly own and operate the Soldier Canyon Filter Plant. Through connections with the three Districts that own the Plant, water is also supplied to the towns of Windsor, Ault, Nunn, Severance, Timnath and Eaton, as well as portions of Pierce and the Northern Colorado Water Association. Approximately 75,000 residents of northern Colorado currently receive drinking water from the Soldier Canyon Filter Plant.

Most of the water treated at the Soldier Canyon Filter Plant comes directly out of Horsetooth Reservoir through an outlet in the Soldier Canyon dam. At this time, approximately 10% of the water treated at the Soldier Canyon Filter Plant originates in the Poudre River. The percentage of Poudre River water treated and delivered to ELCO customers will increase as time goes on. By the Year 2030, it is expected that equal amounts of Horsetooth and Poudre River water will be treated at Soldier Canyon.

Poudre River water is delivered to the Soldier Canyon Filter Plant through the Pleasant Valley Pipeline, an eight mile-long raw water transmission line that also serves water treatment plants owned by Fort Collins and Greeley. Horsetooth Reservoir and the Pleasant Valley Pipeline are part of the Colorado-Big Thompson (C-BT) Project, the largest transmountain diversion project in the State. The Northern Colorado Water Conservancy District administers the C-BT Project. The Conservancy District oversees the delivery of water for agricultural, municipal and industrial uses to almost 1.5 million acres of northeastern Colorado.