Roaring Fork flow study gets underway in Aspen
Work is underway to make sure the Roaring Fork River remains healthy as it winds through Aspen despite upstream diversions and occasional dry conditions.
The Healthy Rivers and Streams program is in the process of hiring a consultant to determine the appropriate flow for each of the seasons, said Pitkin County Attorney John Ely.
The study will concentrate on the stretch of river from the intake to Salvation Ditch, just east of Aspen, to its confluence with Castle Creek. That stretch can be heavily stressed because of numerous diversions.
A minimum streamflow of 32 cubic feet per second was established on the Roaring Fork in the mid-1980s by the Colorado Water Conservation Board, Ely said. That legal decree often isn’t met during dry times. Diverters with senior rights are still entitled to take their fair share of water, so the river flow can drop below 32 cfs.
“You saw what happened in 2002,” Ely said.
The river was reduced to a trickle through town during that drought year. A person could step across cobble stones and easily avoid water in the mostly dry stream bed. The yellow rubber ducks used in the annual Ducky Derby fundraiser were left high and dry.
“It’s obviously unhealthy when there’s no water in the river,” Ely said.
The 32 cfs in-stream flow reflects a level where fish can survive, but it doesn’t necessarily accommodate a healthy river, Ely said. The Healthy Rivers and Streams Citizen Advisory Board wants to determine what the healthy flows would be, keeping in mind the natural seasonal fluctuations.
The board put out a request for proposals for the study this spring and will likely select a consultant by the end of June. Conditions on the river will be studied throughout one full year. Once complete, the goal will be to find ways to achieve what are determined to be the healthy flows, Ely said. He wouldn’t speculate on what those methods might be.
Pitkin County set a precedent last year by becoming the first holder of water rights to donate water to a river to augment the flow. The Colorado Water Conservation Board approved the county’s request to donate 4.2 cfs it can divert from Maroon Creek back to the Roaring Fork River.
The water trust agreement was the first big accomplishment of the Healthy Rivers and Streams program. Pitkin County voters authorized the program in November 2008 and approved a 0.1 percent sales to fund the effort. Those revenues will fund the study of healthy river flows.
Ely said the goal of the effort isn’t to restore historic flows of the river. That’s impractical because it would flood out much of the riverside development. It is also impractical because there are 20 “decent-sized” diverters between the headwaters of the Roaring Fork River and its confluence with Maroon Creek, Ely said.
About 37 percent of the headwaters of the Roaring Fork is diverted to the Eastern Slope, according to the Roaring Fork Conservancy, a Basalt-based nonprofit that monitors water quality and quantity issues in the Roaring Fork watershed. Numerous smaller diversions are made to supply ditches within the valley.
Ely said it might be possible to restore flows that mimic seasonal fluctuations of a healthy river. That would include flows higher enough to scour the riverbed in spring.
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