March 12, 2013

A water gap, and a data gap, along the Roaring Fork River

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Roaring-Fork-River gap

The Roaring Fork River often lacks water as it flows through central Aspen. There also is a lack of data about just how much water is in the river.

The current locations of streamflow gauges above and below Aspen give a falsely upbeat picture of the river’s condition through its driest reach, according to Chelsea Congdon Brundige, the director of Friends of Rivers and Renewables, which has been studying the need for more gauges in the watershed, along with the Roaring Fork Conservancy.

And a recent report funded by a Pitkin County program shows that a new gauge below the Mill Street bridge could help close the data gap. The report, along with a snapshot assessment that tracked water levels, cost the county’s Healthy River and Streams program $28,000.

“You could capture what’s really going on in the Fork,” Congdon Brundige said.

To help define the need and best location for a new gauge, hydraulic consultant Seth Mason of Durango took measurements on the Roaring Fork River under the Mill Street bridge in July, September and October of 2012 — one of the three driest years in Colorado in the last 50 years.

On July 25, 2012, the gauge above Aspen, called “Roaring Fork River Near Aspen,” showed there was 25 cubic feet per second (cfs) of water flowing into town.

That amount of water is below the state’s instream flow right of 32 cfs, which is necessary to protect the environment “to a reasonable degree.”

But even the 25 cfs of water wasn’t in the river for long after flowing past the upper gauge.

The United States Geological Survey gauge is just above three irrigation ditches — the Salvation Ditch, the Nellie Bird Ditch and the Wheeler Ditch — each of which take water out of the Fork before it flows under the Cooper Avenue/Highway 82 bridge east of Aspen.

On July 25, Mason found that the Salvation Ditch alone was diverting 17.4 cfs from the river.

So while the upper gauge indicated the river was flowing at 25 cfs, by the time it got to the Mill Street bridge nearthe Aspen Art Museum, it was only flowing at 5 cfs — well below the state’s environmental flow level.

The next gauge downstream on the Fork below the Aspen Airport Business Center showed the river flowing at a beefy 152 cfs on July 25, primarily due to the addition of water from Castle and Maroon creeks.

Mason found similar circumstances on two dates in September.

On Sept. 6 the upper gauge showed the Fork flowing at 31 cfs, but there was only 17 cfs flowing under the Mill Street bridge. The downstream gauge showed 106 cfs in the river.

On Sept. 18, the upper gauge showed 33 cfs, yet Mason measured just 19 cfs at the Mill Street bridge, and the lower gauge showed 112 cfs in the river.

The current arrangement of the two gauges above and below Aspen “do not collect data on the stream segments experiencing the greatest flow depletion,” Mason wrote in a Feb. 13 report that was recently presented to the county’s Healthy Rivers and Streams board.

And he notes, the data gap is a problem when it comes to developing “definitive conservation and management solutions aimed at improving stream health on this segment of the Roaring Fork River.”

Mason has found that a gauge under the Mill Street bridge would help not only measure the quantity of water, but also help bolster water-quality monitoring efforts.

Sharon Clarke, the watershed action director for the Roaring Fork Conservancy, said the need and desirability of a new gauge on the Fork at Mill Street “was more clear cut” than the need for gauges on seven other high-priority reaches in the watershed that also clearly have data gaps, including lower Maroon Creek, the Crystal River and Brush Creek.

In a June 2012 report, Mason estimated it would cost $13,500 to install appropriate gauging equipment on the Fork at the Mill Street bridge location and another $4,000 in annual maintenance costs.

Bill Jochems, the current chair of the Healthy Rivers and Streams board, said to date his board has been leery of funding new gauges because of their long-term cost.

“We were advised by a former board member, Steve Hunter, to look carefully and to look long term when it comes to locking ourselves into the expense,” Jochems said.

The county’s river program is funded by a county-wide sales tax that generates about $1 million annually.

“It is not easy to raise funds for a gauge because it doesn’t give people a warm fuzzy feeling,” said Clarke, suggesting it was like buying a thermometer for a sick patient.

“It gives them information, but it doesn’t change the situation,” she said.

Editor’s note: Aspen Journalism and the Aspen Daily News are collaborating on coverage of water issues in Pitkin County.

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