Twin Lakes Tunnel opens for more transmountain diversions

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The east end of the Twin Lakes Tunnel on June 6, 2016.

Brent Gardner-Smith/Aspen Journalism

The east end of the Twin Lakes Tunnel on June 6, 2016.

A graph showing the level of water flowing through the Twin Lakes Tunnel this week. The tunnel began diverting water, after being closed for two weeks, on Tuesday, June 28, 2016.

A graph showing the level of water flowing through the Twin Lakes Tunnel this week. The tunnel began diverting water, after being closed for two weeks, on Tuesday, June 28, 2016.

ASPEN – The unnatural order of things was restored Tuesday as the Twin Lakes Tunnel began diverting water to the east again from the headwaters of the Roaring Fork River, after having been closed for two weeks.

The tunnel was closed temporarily after constraints in water rights required that it stop diverting from the Fork, Lost Man and Lincoln creeks, and other tributaries in the headwaters.

The tunnel under the Continental Divide had been diverting about 620 cubic feet per second (cfs) before diversions were stepped down over a three-day period from June 14 to 16, when the tunnel closed.

The reintroduced native flows down the Fork and Lincoln Creek added noticeable intensity to the river as it made its way through the Grottos, Stillwater and Slaughterhouse reaches near Aspen.

One of the constraints on the legal rights of the tunnel is that when the Colorado Canal in Ordway can divert freely because there is plenty of water in the lower Arkansas River, it cannot demand water from the Roaring Fork.

But the spring runoff has slowed, pinching the supply of water available to the canal from the Arkansas. As such, it can now legally call for water from the Roaring Fork.

“The Colorado Canal is being called out, so we can start diverting the tunnel under the direct flow portion of the right,” wrote Kevin Lusk, the president of the board of the Twin Lakes Reservoir and Canal Co. and a principal engineer at Colorado Springs Utilities, in an email Tuesday.

The other constraint was that the Twin Lakes Reservoir and Canal Co. had filled its storage allotment of 54,452 acre-feet of water in Twin Lakes Reservoir.

With that “bucket” filled, and the Colorado Canal still in priority, the tunnel had to be closed.

Not all of the water diverted from the Fork’s headwaters goes to the Colorado Canal, however, as the Independence Pass Transmountain Diversion System, of which the Twin Lakes Tunnel is the key component, now also helps meet water needs in several Front Range cities.

The diversion system is technically owned by the Twin Lakes Reservoir and Canal Co., which is based in Ordway. But Aurora, Colorado Springs, Pueblo West, and Pueblo own almost all of the shares in the company.

On Tuesday, the Twin Lakes Tunnel, which begins at Grizzly Reservoir on Lincoln Creek, was opened back up and about 200 cubic feet per second began flowing east, primarily from Lincoln Creek and the creeks in Brooklyn, New York, and Tabor gulches.

In response, levels in the Roaring Fork River near Aspen fell sharply.

The river at Difficult Campground, for example, was flowing at 390 cfs at 6 a.m., Tuesday morning, but had fallen to 244 cfs by 8 p.m.

And the measuring gauge on Stillwater Drive, just below the North Star Nature Preserve, showed the river flowing there at 510 cfs at 6 a.m. and at 311 cfs by 8 p.m.

On Wednesday, Lusk said that new calls for water from various shareholders in the Twin Lakes Reservoir and Canal Co. mean that water from Lost Man Creek and the main stem of the Fork would soon be added to the flow of water being sent east through the tunnel.

Lusk said he expected the tunnel to continue diverting water through the summer.

This marked the second year in a row the Twin Lakes Tunnel was forced to cease diverting due to wet conditions on the east side of the pass.

During most of the time the Twin Lakes Tunnel was closed, diversions continued to flow as usual through the Bousted Tunnel, which sends water east from the headwaters of the Fryingpan River, as well as from Hunter, Midway, and No Name creeks near Aspen.

Around 800 cfs has been flowing through the Bousted Tunnel for most of June.

And according to the Pueblo Chieftain, the total diversion from the Fry-Ark project so far this year is about 51,000 acre-feet of water.

Add that to the approximately 25,000 acre-feet diverted so far by Twin Lakes, and it means about 76,000 acre-feet has been diverted from the Roaring Fork River watershed so far this year, not counting what may have been sent through the Busk-Ivanhoe Tunnel, which also diverts from the upper Fryingpan.

Ruedi Reservoir, by comparison, can hold 102,373 acre-feet.

Editor’s note:
Aspen Journalism and the Aspen Daily News are collaborating on coverage of rivers and waters. The Daily News published a version of this story on Thursday, July 30, 2016.

Due to a reporting error, the Daily News story needed to be corrected as follows: “A story on Thursday, ‘Transbasin diversions ramp back up at the Twin Lakes Tunnel this week,’ overstated the amount of water diverted from the Roaring Fork RIver headwaters so far this year through the Twin Lakes Tunnel. The tunnel has diverted approximately 25,000 acre-feet of water from the Fork and its tributaries, not 54,452 acre feet, which is the full amount of water that the Twin Lakes Reservoir and Canal Co. can legally store in Twin Lakes Reservoir. The article also then overstated the total amount diverted from the Roaring Fork RIver watershed between the Twin Lakes and Bousted tunnels. Instead of 105,000 acre-feet, approximately 76,000 acre-feet has been diverted this year.”

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