Brent Gardner-Smith/Aspen Journalism
ASPEN – On Tuesday, June 14, the Twin Lakes Reservoir and Canal Co. turned out the flow of Lost Man Creek into the main stem of the Roaring Fork River, instead of sending it under the Continental Divide to Twin Lakes Reservoir.
Lost Man Creek is a major tributary of the upper Roaring Fork River and nearly its entire flow is typically diverted through the Twin Lakes Tunnel.
The creek flows out of a sweeping high country valley and runs into Lost Man Reservoir. It’s then diverted into a canal and dumps into the main stem of the Roaring Fork River behind a dam.
That dam doesn’t form a reservoir, but instead diverts water from both Lost Man Creek and the Fork into a tunnel under Green Mountain and then, after another stretch of canal, into Grizzly Reservoir.
Once water from Lost Man Creek and the main stem of the Roaring Fork reaches Grizzly Reservoir it joins water from Lincoln, New York, Brooklyn, and Tabor creeks and normally flows into the Twin Lakes Tunnel. The water in the tunnel daylights into Lake Creek and flows down to Twin Lakes Reservoir in Twin Lakes, Colo.
From Twin Lakes Reservoir, all of the water collected and diverted by what’s officially known as the Independence Pass Transmountain Diversion System is sent to Aurora, Colorado Springs, Pueblo West, Pueblo, and fields in the lower Arkansas River basin.
But due to constraints in its water rights, Twin Lakes Reservoir and Canal Co. is being forced to curtail its diversions from the Independence Pass system, which means in all, 600 cfs of native flows will be turned out Wednesday and will flow either into the main stem of the Fork or upper Lincoln Creek, which flows into the Fork just above the Grottos.
On Tuesday, just flows from Lost Man Creek and the Fork were turned out from the diversion system, adding about 250 cfs to the Fork as it flowed past Lost Man Campground.
On Wednesday, the flows from the Lincoln Creek side of the system will be added to the released native flow of water heading downstream toward Aspen. (Update: On Tuesday, officials with Twin Lakes made the call to delay shutting the Twin Lakes Tunnel until Thursday, June 16.)
The Twin Lakes Tunnel, which has been diverting over 600 cfs since June 6, is set to be closed at noon Wednesday, according to Kevin Lusk, the president of the board of Twin Lakes Reservoir and Canal Co. and a senior engineer with Colorado Springs Utilities, which owns 55 percent of the water diverted from the upper Fork.
The Twin Lakes Tunnel is expected to be closed for two to three weeks and the return of native flows to the Fork – for the second year in a row – may flood the North Star Nature Preserve and create what some locals called “Lake North Star.”
Last year, when the Twin Lakes Tunnel closed, the Fork peaked at the “Roaring Fork Near Aspen” gauge at 1,680s cfs on June 18.
Tuesday evening, flows in the Fork at the “Roaring Fork Near Aspen” gauge, at Stillwater Drive, were at 640 cfs, up from 400 cfs before the flow of Lost Man Creek was returned to the Fork.
With the addition of Wednesday (now Thursday) of about 350 cfs coming down Lincoln Creek, the flows at Stillwater Drive could reach the 1,000 cfs range. The Fork, at its confluence with the Colorado River in Glenwood Springs, was flowing at 4,150 cfs on Tuesday night.
Hot and sunny weather expected over the next week in the Aspen area will also likely drive up the flow in the river.