Monday, May 9, 2011

Warm weather triggers increased snowmelt

Warm weekend temperatures increased the inflow to Willow Creek Reservoir. Right now we are holding the reservoir's elevation steady at around 8,092 feet and passing inflows right through. The highest release so far this year was 782 cfs at 9:45 this morning.

Releases from Lake Granby are holding steady at about 400 cfs. Below the dam at Lake Granby there are small side tributaries that add to the flow of the river, so flows can be higher by the time they reach the "Y Gage" (listed as "Colorado River near Granby, CO" on the USGS website). Saturday evening was a good example: the flows were at 600 cfs, so the tributaries likely contributed about 200 cfs. The flow has not been as high since then.

The schematic shown with this post shows the various stream gages below Willow Creek Reservoir and Lake Granby. The releases from Granby and Willow Creek reservoirs, along with the flow of the Fraser River, all add to the Colorado River's flow as measured below Windy Gap Reservoir. Today, that flow went above 2,000 cfs for the first time this year. The flows are affected by Denver Water's diversions; they aren't diverting much Fraser River water right now because it has been so cold.