Denver Water increases reservoir outflows to Blue River |

Denver Water increases reservoir outflows to Blue River

Portions of the Blue River Trail in Silverthorne were underwater on Tuesday, May 26, 2015, near Bald Eagle Road. Denver Water has increased outflows from Dillon Reservoir to 1,500 cubic feet per second (cfs) to help with flood protection once snowmelt begins in earnest. The utility tries to maximize outflows to the Blue River at no more than 1,800 cfs, and once the reservoir is full there is little Denver Water can do to control flows, so the annual balancing act has begun.
Bill Linfield / Contributed |


May 26, 2014

Snowpack: 18.1 inches of water

Dillon Reservoir elevation: 8,995 feet

Reservoir inflow: 1,484 cfs

Outflow to Blue River: 1,100 cfs

May 26, 2015

Snowpack: 18.4 inches of water

Dillon Reservoir elevation: 9,011 feet

Reservoir inflow: 475 cfs

Outflow to Blue River: 1,500 cfs

Source: Denver Water

Over Memorial Day weekend, Denver Water increased the outflow from Dillon Reservoir to the lower Blue River.

The utility raised outflows below Dillon Dam from about 900 cubic feet per second on Friday, May 22, to roughly 1,500 cfs by Monday in hopes of creating more space in the reservoir ahead of this year’s peak runoff.

Denver Water spokesman Travis Thompson said the utility is not legally allowed to take more water under the Continental Divide through the Roberts Tunnel than is needed by Front Range and Eastern Slope customers. Because of high flows in the South Platte River and low customer water use, Denver Water doesn’t expect to take water through the tunnel until mid-July or later.

On Tuesday, Thompson said, Dillon Reservoir is 92-percent full, which is typical for this time of year.

Though the reservoir’s current inflow is much lower than it was in 2014, water managers expect to see a dramatic increase in the coming weeks as snowpack above the reservoir is above-average and has surpassed even last year’s snowpack.

Every spring, Denver Water coordinates with local government officials, and water managers to try to prevent flooding in Silverthorne.

As a rule of thumb, 200 to 550 cfs on the Blue River below the dam is the ideal flow range for fishing, while 400 to 1,300 cfs is ideal for rafting.

At 1,500 cfs, flows start to create safety concerns for rafting, and, by 1,800 cfs, the Blue River’s banks can start to overflow.

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