Summit County Citizens Voice

Denver Water warns of possible high flows in Lower Blue

Record snowpack and warming temps could combine to lead to flooding downstream of Dillon Reservoir. PHOTO BY DYLAN BERWYN.

By Summit Voice

SUMMIT COUNTY — The latest snowpack measurements and weather forecasts have prompted Denver Water to warn residents of the Lower Blue Valley, below Dillon Reservoir, to be prepared for flooding flows in the Blue River.

Combined inflows into the reservoir from the Upper Blue, the Snake River, Tenmile Creek and various smaller tributaries are forecast to peak in the range of 2,800 to 4,100 cubic feet per second. the average this time of year is about 1,700 cfs, and the record peak, set in 1995, is 3,408 cfs.

Denver Water tries to operate the reservoir so the peak outflow does not exceed 1,800 cfs, which is approximately the “bank-full” condition for the Blue River downstream of the dam. Because of this year’s exceptionally high snowpack and the uncertainty of the amount, timing and rate of the melt, it may not be possible to keep the peak outflow below 1,800 cfs, Denver Water said in an advisory bulletin issued June 3.

The utility lowered the reservoir to a nearly unprecedented level for this time of year. The only time it’s been lower than this in early June was after two major droughts, in the late 1970s and again in 2003.

“We can only lower the reservoir so much, but we intend to operate the system consistent with the outflow goal, while also fulfilling our legal and service-related obligations,” But Bob Steger, Denver Water’s manager of raw water supply, wrote in an email to local officials.

Denver Water will continue to monitor conditions and provide updates as they become available; however, residents and businesses along the Blue River downstream of Dillon Dam should be prepared for flows in excess of 1,800 cfs in the upcoming months. Currently, the outflow is 1,300 cfs and Denver Water likely will increase outflow to 1,400 cfs this afternoon and through the weekend. The current inflow to Dillon Reservoir is about 1,600 cfs.
The Summit County High Water Preparedness brochure is available on the Summit County Government website at http://www.co.summit.co.us, and contains locations for sand and sandbags as well as other flood-related resources. To sign up for the SCAlert emergency notification system, visit http://www.scalert.org.

Filed under: climate and weather, Colorado, Dillon Reservoir, Environment, flooding, La Niña, rivers, seasons, Snow and weather, Summit County Colorado, Summit County news, Summit County snow and weather, water Tagged: | Blue River, Colorado flooding, Colorado record snowpack, Denver Water, Dillon Reservoir, lower blue, Summit County Colorado, Summit County News, Tenmile Creek