June 10, 2010 - The inflow to Dillon Reservoir over the past few days has been considerably higher than what was forecasted. As a result, there have been questions about potential flooding below the dam.
“As long as it doesn’t diminish our water supply, we do our best to operate the system in a way that is beneficial to Summit County,” said Bob Steger, manager of raw water supply. “We work to keep the flows coming out of Dillon Reservoir to 1,800 cubic feet per second (cfs) or less to help prevent flooding, but there’s only so much we can do to help manage the high flows Mother Nature is throwing at us this year.”
Denver Water has the difficult job of responding to the variables of weather and customer water needs while operating its system to comply with the Blue River Decree, which says the utility only can take water from the West Slope for use on the East Slope when there is a need for it.
Dillon Reservoir began spilling May 24. This past Sunday, Denver Water began running water through the Roberts Tunnel to fill up its South Platte Reservoir storage — space created when a river call for the South Platte Basin was placed on June 4. By starting the tunnel, the amount of water flowing out of Dillon Reservoir to the Blue River was reduced. Depending on conditions in the South Platte Basin in the next couple of days, the utility may have to reduce the flows through or shut off Roberts Tunnel to avoid wasting water it cannot use and remain in compliance with the Blue River Decree.
The utility also has been operating the discharge gates at Dillon Reservoir to manage the amount of water that goes downstream. This operation depends on the amount of water coming into the reservoir.
Denver Water has been monitoring the reservoir outflow multiple times a day and at night to make decisions about how much water to release through the discharge gates. The goal is to keep the total outflow below 1,800 cfs; whether or not this goal can be met depends on the amount of water going into the reservoir and how much water is needed to supplement the utility’s South Platte supplies.
Denver Water will continue to closely monitor the situation and update local officials and the media of its work to help mitigate the situation. Local authorities have prepared a plan of action to respond to possible high water events. Sandbags are available at various locations throughout the County, and property owners who feel their property may be affected by high water are encouraged to utilize these materials. A High Water Preparedness Packet is available at www.co.summit.co.us/emergencymanagement.