Federal water authorities signed off Friday on the $300 million Windy Gap Firming Project to siphon more water out of the Colorado River Basin into a huge new reservoir for the high-growth Front Range.
The west-flowing river water — up to 8.4 billion gallons a year pumped back eastward and under the Continental Divide — is expected to meet the needs of 400,000 residents around Broomfield, Longmont, Loveland and Greeley.
A U.S. Bureau of Reclamation decision clears Northern Water to build the 29 billion-gallon Chimney Hollow Reservoir, assuming it obtains state water quality and federal wetlands permits.
The reservoir would sit southwest of Loveland, west of Carter Lake. Work would begin by 2018, Northern Water spokesman Brian Werner said.
“It’s going to make water supplies more reliable,” Werner said. “You want to make sure you have a firm supply year in, year out so you have water for the basic needs of your communities.
“With all the growth we’ve seen in northern Colorado, we keep pushing that envelope of how close we are when that really dry year hits. We’ve got a lot more people moving in — one of the fastest-growing populations in the country — and part of this is about preparing for the future.”
For more than a decade, western Colorado communities have fought the project, contending it will degrade the ailing Colorado River Basin.
The project would divert river water near Granby and pump it through an existing 9-foot-diameter tunnel under the Continental Divide, to be stored in Chimney Hollow.
Numerous studies have found this will increase environmental harm that began in the 1930s, when federal agencies began pumping west-flowing water back eastward, through the Adams, Moffat and other tunnels, to Colorado’s semi-arid Front Range. Water temperatures spiked. Algae spread. Sediment clogged channels and choked aquatic life.
Negotiations during the past six years led to plans to try to minimize environmental harm and offset damage.
Northern Water has agreed to:
• Install temperature-monitoring devices and not divert water when the river gets too warm.
• Release trapped water for 50 hours at least once every three years, ensuring flows of 600 cubic feet per second, to simulate natural floods essential for ecosystem health.
• Give 977 million gallons a year to Grand County.
The project would increase the amount Northern Water diverts annually to more than 250,000 acre-feet, bringing total water diverted from the Colorado River Basin to 67 percent of the natural flows. Northern Water supplies 33 cities and irrigation water for 650,000 acres of crops.
Bruce Finley: 303-954-1700, bfinley@denverpost.com or twitter.com/finleybruce
