Crews Make Improvements at Shadow Mountain Reservoir Spillway

Crews from Northern Water and Dietzler Construction did important work in September and October to make repairs on the spillway at Shadow Mountain Reservoir in Grand County. 

Shadow Mountain Reservoir is a vital piece of the Colorado-Big Thompson Project, receiving water pumped from Lake Granby and delivering it to Grand Lake and then to points on the East Slope via the Alva B. Adams Tunnel. Inspections had determined work was required on the spillway concrete, which receives water each spring from the high inflows into both Grand Lake and Shadow Mountain Reservoir from the Colorado River and its tributaries. 

In the project completed this fall, as featured in this new video, crews replaced much of the floor of the spillway with new concrete and reinforcement steel to ensure the spillway would work as intended for years to come. In 2026, additional work will be needed on the side panels of the spillway, and that work will be announced in advance of its execution.