Granby Dam flows to increase May 1 |

Granby Dam flows to increase May 1

A small stream of water flows over the Lake Granby spillway last summer during maintenance on valves in the spillway.Water officals are increasing flows from the lake into the Colorado River starting this week in anticipation of the lake spilling as the spring runoff increases.
Sky-Hi News file photo | Sky-Hi News

The U.S. Bureau of Reclamation and Northern Water will be increasing the water releases from Lake Granby on Friday, May 1.

Operators will ramp up releases to 430 cubic feet per second through the outlet valves, which will enable reservoir operators to better manage peak spills later this spring.

With the Colorado-Big Thompson Project reservoirs at record storage levels for late April, the likelihood of spills at Lake Granby are a near certainty.

“What we are trying to do by increasing releases now is reduce the peak of the runoff to alleviate flooding concerns below Granby,” said Noble Underbrink, Collection Systems Department manager for Northern Water.

Northern Water and Reclamation are completing a maintenance and repair project on the Lake Granby spillway. Once complete by mid-May, reservoir operators will route the peak flows through the spillway to the Colorado River downstream.

“Working together, we can alleviate the flooding concerns below Granby and maximize the amount of water we can store in the Colorado-Big Thompson Project, “ Eastern Colorado Area Office Manager Jacklynn Gould said.

Lake Granby is currently at 92 percent of capacity, about 6 feet from full.

The current forecast is that operators will be able to keep the spills to below the amount at which downstream flooding occurs.

Underbrink said the pre-emptive releases have been used many times in previous years.

“With the C-BT reservoir system nearly full, the forecasts indicate there will be more runoff than the reservoirs can hold.”

The flows and forecasts will be monitored and adjustments made accordingly as inflows pick up during the next few weeks.

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