#BlueRiver flow is above average following rain on the Western Slope and Front Range — The Summit Daily #ColoradoRiver #COriver #aridification

From The Summit Daily (Taylor Sienkiewicz):

On July 1, the Blue River below Dillon was flowing at 221 cubic feet per second. On Aug. 5, it jumped up to 455 cfs. Nathan Elder, manager of water supply for Denver Water, explained that in the first week of August, the Blue River’s flow reached the 450 mark and has slowly declined since. On Tuesday, Aug. 10, it was 340 cfs, which he said is slightly above normal for this time of year.

Map of the Blue River drainage basin in Colorado, USA. Made using USGS data. By Shannon1 – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=69327693

Denver Water manages Dillon Reservoir, which the Blue River flows into and out of.

“We’re trying to match outflow with inflow and send that water downstream to Green Mountain Reservoir,” Elder said…

The increase in water to Green Mountain Reservoir is welcome, as the reservoir was over 50,000 acre-feet below normal in late July, and a downstream call for irrigation rights was placed on the reservoir. As of Aug. 11, the reservoir, which is full at about 154,000 acre-feet of water, was holding 100,243 acre-feet of water.

Summit County saw its wettest July in 10 years, which is what has contributed to the increase in outflow, Elder said. He noted that not only has the rain on the Western Slope helped, but rain on the Front Range has lowered water demands on that side of the Continental Divide. That has reduced the need to send water through Roberts Tunnel, which has kept more water in Dillon Reservoir and made way for the release of more water down the Blue River and into Green Mountain Reservoir…

Dillon Reservoir started out the year lower than normal, and less water flowed in from the melting snowpack. In late June, Elder reported that the reservoir was full but only because much less water was released from the reservoir to the Blue River than in an average year. The lack of water flowing into the Blue River meant two things: Less water went to Green Mountain Reservoir, and commercial rafting couldn’t happen on the river this year…

Goose Pasture Tarn. Photo credit: City of Breckenridge

As for the Goose Pasture Tarn, which is currently lowered due to the rehabilitation of the dam, Elder said the tarn’s water that is being stored in Dillon Reservoir has a “very small impact.” For context, the tarn is 771 acre-feet, whereas Dillon Reservoir is over 257,000. Once it’s time for the tarn to be refilled, it will be given priority for water rights.

Denver Water relies on a network of reservoirs to collect and store water. The large collection area provides flexibility for collecting water as some areas receive different amounts of precipitation throughout the year. Image credit: Denver Water.

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