Summit County Citizens Voice

Denver Water raises outflow from Dillon Reservoir, cuts diversions through Roberts Tunnel, expects reservoir to fill in about 2 weeks

The Lower Blue is flowing at about 1,750 cubic feet, just below flood stage.

A sign at the base of the dam gives information on the history of the facility.

By Summit Voice

SUMMIT COUNTY — The Lower Blue River is flowing perilously close to its banks, as Denver Water increased the flow to 1,750 cfs Thursday. Flooding issues along the Lower Blue start to become more serious at a flow of about 1,800 cfs, but Denver Water’s Bob Steger said he’s hoping the inflow will soon begin to decrease, as predicted by the Colorado Basin River Forecast Center.

Denver Water is also reducing its diversions via the Roberts Tunnel from 250 down to 100 cubic feet per second, as the Front Range reservoirs in the system are nearly full.

Thursday morning, the reservoir was at 9014.17, which is 2.83 feet below the spillway and 0.17 feet higher than Wednesday morning. The average inflow during the last 24 hours was 2,205 cfs. If the inflow stays steady, the reservoir would fill in about 13 days.

Once the reservoir is completely full, water spills through an overflow system into the Blue River below. At that point, Denver Water doesn’t have much control over how much water flows down the valley, as it depends on the inflow. The utility can influence the water level to some degree by changing the diversion amount in the Roberts Tunnel, but that part of the system is not used for flood control. Use of water going through the Roberts Tunnel is subject to very specific conditions under various water decrees.

The wild card in the equation is the rainfall. Strong and persistent thunderstorms could keep the inflow higher than predicted, filling the reservoir more quickly. Thunderstorms are in the forecast through the middle of next week.

Filed under: climate and weather, Colorado, Dillon Reservoir, Environment, flooding, rivers, Silverthorne, Summit County Colorado, Summit County news, Summit County snow and weather, water Tagged: | Blue River, Cubic foot, Denver Water, Dillon Reservoir, flooding, Front Range, Reservoir, rivers, Summit County Colorado, Summit County News