Northern Front Range water supply safe in spite of fires — for now — The #Greeley Tribune

Colorado Rivers. Credit: Geology.com

From The Greeley Tribune (Cuyler Meade):

…while a significant portion of the water supply that is held and accessed by the project that serves the northern Front Range communities is impacted by the fires, the water supply itself is not in danger.

According to Jeff Stahla, public information officer for the Northern Colorado Water Conservancy District — or simply Northern Water — the near-term supply is fine.

The decision to close off a tunnel — which transports water pumped from Lake Granby to Shadow Mountain Reservoir before traveling by gravity through the tunnel through Rocky Mountain National Park to Lake Estes and elsewhere, before eventually settling in Horsetooth Reservoir and Carter Lake in Fort Collins and Loveland — will not impact the water supply that’s eventually drawn from those two reservoirs to supply much of Northern Water’s million-plus customers in Northern Colorado, including Greeley.

That’s because, Stahla explained, the system is proactive. While new water will not be replenished quite according to the normal schedule in the Horsetooth and Carter Lake reservoirs, that water is, in essence, paying down a future withdrawal that won’t happen for a year or more…

“The water coming out of your faucet now, if it’s this project’s water, was probably snow that fell in maybe 2018,” Stahla explained. “It ran off in spring of ’18 and filled up Lake Granby, and then around the end of 2018 into 2019, it would’ve been used to fill up reservoirs on the front range. That would’ve happened over winter of 2018-2019, and then it would’ve been in reservoirs all of 2019 and probably drawn out now in 2020. This project works on a multi-year cycle of gathering runoff, feeding reservoirs and serving the public.”

The water is still in Lake Granby, but temporarily won’t be pumped up to Shadow Mountain because of concerns that the fire will impact the power supply to the pump at Lake Granby…

However, that water is only a portion — a very sizable portion, close to half — of the water that is used by Greeley customers, according to city of Greeley water and sewer director Sean Chambers.

And, truly incredibly, the other major sources of water, four in total, from which the city draws its 20,000 to 25,000 acre feet-per-year supply are also being impacted by these unfathomable wildfires.

“We have water from four different river basins,” Chambers said. “We get water from the Poudre River Basin, that’s where the year-round treatment plan by Bellevue, northwest of For Collins is. The top of the Poudre is where the fire started. You go north and cross into Laramie River Basin — the Laramie flows north into Wyoming but we have a system of ditches and tunnels that brings water back into the Poudre. The fires burned a bit of the headwaters of the Laramie. We also get water from the Big Thompson Basin, and the Cameron Peak Fire spread southeast over the last ten days, blown over the ridge line and the divide into the Big Thompson Basin. And then the last basin is the Colorado River Basin, which is where the East Troublesome Fire comes from.”

Chambers, marveling, called this phenomenon the first time “in recorded history” that this has happened, where all four major water sources are affected by fires at the same time…

Further, while snow melt over burned land could well impact other water sources as well, there are plans in place, Chambers said.

“When the High Park Fire happened, that fire had these post-precipitation water-quality events in the river, where Fort Collins and Greeley and others, who take water directly off the Poudre River for municipal treatment, we turned off our intakes and let the bad water go by, let the water quality improve. We can do that because of the beautiful supplemental supply in the Colorado Big Thompson project.”

The flexibility requires planning, though, including, Chambers said, installing source-site filtration systems where snow runoff on its way the river systems are filtered prior to entering the water supply…

In the immediate moment, though, the water supply even well into next year is in good shape, regardless of the fires Stahla said.

“Not even just into early next year,” Stahla said. “Reservoirs are there for that kind of demand management that you can have some stocked away close to meet your needs. As of now, there’s no operational changes because of the wildfires to the water supply on the Northern Front Range. Those reservoirs will be refilled by next spring.”

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