Eyeing the Eagle
That could prompt the first-ever summer releases of water stored in three headwater reservoirs: Homestake, Black Lakes and Eagle Park. Those releases of up to 5 cubic feet per second, or cfs. will be triggered when the flow of the Eagle River at the Avon water treatment plant reaches 25 cfs, a record low.
The river Wednesday was flowing at 68 cfs. At current rates of decline – and a continued lack of rain – a trigger point may be reached sometime next week.
The low flow reflects the release from Homestake Reservoir of 20 cfs by the cities of Aurora and Colorado Springs Tuesday afternoon, under order from the state water engineer.
Colorado and much of the West in experiencing a drought – now in its fifth year – that has produced the driest conditions in more than 500 years.
When the 25 cfs level is reached and maintained for 72 consecutive hours, a ban on all outside irrigation will be enacted.
Irrigation accounts for up to 70 percent of all water use. At their peak water production, local water plants require nearly 15 cfs from rivers and streams. If the Eagle River falls beneath that flow at Avon, the water plant won’t have enough water.
“We don’t have any water releases scheduled,” said Dennis Gelvin general manager of The Eagle River Water and Sanitation District, which oversees water service for 22,000 residents in eastern Eagle County.
“When we hit the trigger point of 25 cubic feet per second, we will move to the next level of water restrictions.”
Local streams are heavily diverted for domestic use, as well as for surface irrigation, under a prioritized system of water rights. Some experts says current Colorado water law actually encourages water consumption, not conservation.
Gelvin said he’s not too worried about the immediate future. It’s the outlook for the next six dry months that concerns him. When the growing season ends, so too will the demand for water for irrigation, he said. That will help, but the flow of area steams is likely to continue to decline.
“We could see flows in the teens in October,” he said. “We could see the river freeze solid if there isn’t enough water in it.”
That could trigger additional releases of water from the three reservoirs. The upper valley water districts have stored nearly 1,250 acre-feet – approximately a four-month supply at a flow rate of 5 cfs.
Those districts typically release water in the winter to help provide water in streams for domestic consumption.
“If we make it to mid-December to make the releases, we should be all right,” Gelvin said.
The releases will be made initially from Homestake Reservoir, where the water districts have 250 acre-feet awaiting release. At a flow rate of 5 cfs, that’s about 25 days’ worth.
There is an element of unknown in releasing water in a dry year, however, because not all the water released can result in higher streamflows. Some of it will be absorbed into the streamside aquifer. How much remains a question.
When the water district released water last winter from the Black Lakes, atop Vail Pass, that water never increased the flow of Gore Creek at the water plant on Forest Road in Vail, said District Engineer Linn Schorr.
Water for Vail residents now is derived from wells in East Vail. Drawing water from that aquifer causes lower flows in Gore Creek. When water is released, it apparently replenishes the water drawn down aquifer by the wells, said hydrologist Bob Weaver of Hydrosphere in Boulder.
That could happen too with releases aimed to augment flows of the Eagle River. How much remains the question Weaver said.
But when winter’s icy grip hits, it makes local streams more efficient at delivering water because the banks freeze and don’t absorb as much water, said Gelvin.
The water districts have 300 acre-feet in the Black Lakes, 250 in Homestake and 700 in Eagle Park. Those reservoirs should be replenished by winter snow – assuming it falls.
Plans are afoot to increase the storage at Eagle Park, said Schorr, and a new diversion aimed at scooping water from the east fork of the Eagle River could be in place for next spring’s snowmelt.
That will increase the volume of stored water available for water users in the upper valley to 1,650 acre-feet.