#Runoff news: With Twin Lakes diversion off the Roaring Fork will see an extra 550 cfs for a while

Grizzly Reservoir on Lincoln Creek, well above its confluence with the Roaring Fork River. The reservoir briefly stores water before it is diverted under the Continental Divide.

From The Aspen Daily News (Curtis Wackerle):

Diversions from the Roaring Fork River’s headwaters to the Eastern Slope ceased on Thursday and are expected to be offline until the seasonal runoff slows down, possibly weeks from now.

Bruce Hughes, general manager of the Twin Lakes Reservoir and Canal Co., said that his entity, which controls the diversion of water from the upper Roaring Fork Basin to the Arkansas River Basin, is hitting the maximum amount of Western Slope water it can store in Twin Lakes Reservoir. In addition, water users on the East Slope that typically rely on Roaring Fork flows are able to meet their needs with native Arkansas Basin runoff.

“Legally we cannot take anymore,” Hughes said, adding that “we are still looking at quite a spell” before diversions can resume — possibly two or three weeks.

That means that as much as 550 cubic feet per second of water that is normally diverted through a 4-mile-long tunnel underneath the Continental Divide will stay in the watershed, adding to the already high flows coming down the Roaring Fork.

Add that to the impacts of a historic winter snowpack, which, thanks to a cold and wet spring, is in the top 10 of longest-lasting snowpacks, according to records kept by the Roaring Fork Conservancy.

The Roaring Fork River, measured at Aspen, likely saw its natural seasonal peak early Tuesday morning, when it hit 1,020 cfs. Flows began trending down after that, but they shot back up when the transbasin diversions ceased. Flows through Aspen cracked the 1,000-cfs threshold again on Friday, creating the fourth distinct peak since June 15.

The river will continue to flow naturally until the tunnels are turned back on. The Twin Lakes Reservoir and Canal Co. manages the system that collects water from the Roaring Fork River and from Lost Man, Grizzly, Lincoln, New York, Brooklyn and Tabor creeks, and delivers the water to Grizzly Reservoir. From there it is sent through the 4-mile-long Twin Lakes Tunnel, under the Divide, into Lake Creek and down to Twin Lakes Reservoir, on the east side of Independence Pass and a short distance from­ the confluence of Lake Creek and the Arkansas River.

Lincoln Creek. Photo: Brent Gardner-Smith/Aspen Journalism

From The Aspen Times (Scott Condon):

There was a bit of an unknown when the Twin Lakes Reservoir and Canal Co. announced earlier in the week that diversions to the Front Range would cease Thursday, resulting in an increase in the water in Lincoln Creek and the Roaring Fork River. The water company’s allotment at Twin Lakes on the other side of the Continental Divide filled Thursday. As a result, an additional 550 cubic feet per second of water started flowing into the Roaring Fork River starting at about 1 p.m. Thursday.

Pitkin County Emergency Manager Valerie MacDonald said higher flows in the Roaring Fork River were evident Friday morning compared with Thursday evening. Twin Lakes officials told her the water levels released into the Roaring Fork wouldn’t exceed 550 cfs. In addition, runoff levels are easing. As a result she doesn’t expect problems with flooding.

The National Weather Service has issued a flood advisory for the Roaring Fork River near Aspen, but only minor lowland flooding is expected.

“This heavy runoff will cause the Roaring Fork River to hover near to above bank full stage into early next week,” the weather service office in Grand Junction said in a notice. Bank full stage is 4.0. Flood stage is 5.0. The river was expected to rise to 4 feet by early morning today, according to the weather service…

The U.S. Bureau of Reclamation decreased releases from Ruedi Reservoir from 917 cfs to approximately 717 cfs on Friday morning. Ruedi Reservoir is expected to fill to capacity today or tonight. And right on cue, inflow to the reservoir is expected to plummet. The forecast by the Colorado Basin River Forecast Center showed in the inflow falling below 900 cfs starting today.

Basalt Police Chief Greg Knot said no problems were reported on the Fryingpan River through Basalt during the period of highest releases…

A flood advisory was canceled Thursday for the Crystal River. The weather service said the river crested at 4.5 feet near Redstone and would continue to fall. Flood stage is 5.0.

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