Denver Water says Dillon Reservoir will ‘fill and spill’ this year, bringing projections for increased flows for the Blue River

Dillon Reservoir is pictured Wednesday, June 30, 2022. The reservoir is expected to fill soon, and outflow projections have increased following a wet spring this year.
Photo by Nicole Miller/Summit Daily News archive

Editor’s note: This story has been updated with the correct outflow averages for the Blue River at the Dillon Reservior.

To decrease the risk of high flows, outflow from the Dillon Reservoir and into the Blue River will ramp up from 100 cubic feet per second to 400 cfs by Friday, June 9.

Denver Water, which manages water levels at Dillon Reservoir, predicted a mild runoff season in May, but higher-than-anticipated precipitation has changed the projections “dramatically,” according to an update from Denver Water.

“We have adjusted our outflow projections from 500 cubic feet per second to a peak of 1,400 cfs, and Dillon will “fill and spill” this year,” Denver Water wrote in its update.

As of Tuesday evening, Dillon Reservoir was 94% full, and outflow was reported around 100 cfs compared to an average outflow of around 640 cfs. The reservoir is typically 95% full this time of year, according to Denver Water reports.

“There is a limited possibility that continued rain could result in a situation where we need to release more than 1,800 cfs, which would result in flooding downstream,” Denver Water warned in its report.

Denver Water says the updated projections mean that the Blue River will likely be able to support commercial rafting for about two weeks sometime in mid-June. Commercial rafting often requires flows higher than 500 cfs.

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