#Runoff news: @DenverWater is drawing down Dillon Reservoir in anticipation of big #snowpack melting-out

Grays and Torreys, Dillon Reservoir May 2017. Photo credit Greg Hobbs.

From the Summit Daily (Deepan Dutta):

This year, instead of supplying helicopters with water to dump on fires, Denver Water is draining water from Dillon Reservoir in anticipation of runoff, which is expected to really begin coming down in the next few weeks.

“This year being a high snowpack year, we know there’s going to be a lot of water getting into the reservoir,” Denver Water supply manager Nathan Elder said. “We’re trying to have enough space to catch that runoff while providing for safe outflows to the Blue River below the reservoir.”

[…]

At the moment, the reservoir — which is the main drinking water supply for 1.4 million people in the Denver metro area — is 75% full with 192,554 acre-feet of water. When full, the reservoir holds 257,304 acre-feet. An acre-foot of water would cover an area the size of an acre 1-foot deep. Given the current estimate for runoff volume, there will be more than enough water to fill it.

“The forecasting for the rest of June and July project a volume of anywhere from 169,000 acre-feet to 211,000 acre-feet coming into the reservoir,” Elder said. “That’ll fill it, but we’re probably not going to fill it until the Fourth of July to make sure we’re past that peak-inflow time.”

Elder said peak inflow to the reservoir is expected to start about a week later this year than usual, which also means Summit’s two marinas in Dillon and Frisco will have to wait before the reservoir is full enough for boating. However, boaters should have a lot more time for play this year compared with last, when boat ramps were retracted weeks before they normally would be due to low water.

“Typically, every year we target June 18 to be at 9,012-foot elevation needed for both marinas to be completely operational, but it’s going to be a little delayed this year,” Elder said. “But while the boating season might be shortened by a week on the front end, on the tail end, it should last quite a bit longer.”

The delay also means local emergency officials will be watching streamflows longer into the month, looking to spring into action if Tenmile Creek, Straight Creek or the Blue River approach the verge of flooding.

Current two-week projections show all three waterways approaching “action stage,” the threshold at which the towns and county are called to start flood mitigation preparations, by June 15.

Summit County’s director of emergency management Brian Bovaird said he closely has been watching the forecasts for flooding. That is opposed to last June when Bovaird, who recently had gotten the job as emergency director, was given a literal trial by fire.

“It’s like picking your poison,” Bovaird said. “Last year, it was wildfire. This year, it’s flooding. We’re expecting heavy runoff moisture, which is good for wildfire but makes us uneasy about the flooding risk.”

Barker Reservoir

From Patch.com (Amber Fisher):

Barker Dam’s scheduled spill is expected to begin over the next few days, officials said. Each spring as temperatures warm, runoff from melting mountain snow increases stream flows. Before peak stream flows occur at lower elevations, like in the City of Boulder, mountain reservoirs must first fill and start spilling, officials said.

“This is a normal and expected event that will increase flows in Boulder Creek throughout the city,” The City of Boulder said in a statement.

The Barker Dam spill normally occurs between mid May to late June, but is dependent on weather, snowpack and early spring reservoir levels. This spring, cool temperatures and continued snow accumulation have delayed snowmelt runoff, the city said.

From KJCT8.com (Nikki Sheaks):

The waters of the Gunnison River are currently at 10.7 feet. It has passed the bankfull stage. This means some water is beginning to spill out into the floodplain. The floodplain is the low-lying area next to the river. The Gunnison’s Flood stage is at 13 feet. It’s expected to rise near 10.8 feet by Saturday.

Orchard Mesa and Whitewater are under the current advisory.

Parts of the Colorado River are rising, but it’s not under an advisory. The Colorado River near Loma is nearing bankfull. According to data from a National Weather Service gauge near the state line, water levels are at about 10.5 feet and are expected to rise to 12.5 by Saturday afternoon.

PHOTO CREDIT: McKenzie Skiles via USGS LandSat
The Great Salt Lake has been shrinking as more people use water upstream.

From The Deseret News (Amy Joi O’Donoghue)

The south arm of the Great Salt Lake is up by 2.5 feet since December and its north arm is 2 feet deeper thanks to the wet water year, and the Western Hemisphere’s largest saltwater lake will take on even more water in the weeks to come.

“It’s a pretty good jump so far, but we’re not done yet,” said Todd Adams, deputy director of the Utah Division of Water Resources.

The highest elevation snowpack has yet to melt, and with most reservoirs brimming, that water will bypass those storage infrastructures and help quench the thirsty saltwater body…

Water managers along the Wasatch Front will be keeping their eye on stream flows and reservoir levels to keep enough storage going into the summer and time releases into rivers to hopefully avoid flooding.

While most reservoirs are already full, Echo above East Canyon sits at just 49 percent of capacity and Rockport sits at 78 percent, ready to take on snowmelt.

“We could have filled it (Echo) twice this year,” said Tage Flint, general manager of the Weber Basin Water Conservancy District. “The peak flows have not occurred yet coming out of the Uinta Mountains coming down the Weber River, so we are purposefully leaving Rockport down some and Echo down more to use them as shock absorbers to take those big flows.”

Much of that extra water will be sent on downstream to the Great Salt Lake…

The lake is critical to wildlife, multiple industries, recreation interests and more, contributing $1.3 billion into Utah’s economy and drawing tourists from all over the globe.

It serves as the Pacific “flyway” for thousands of migratory birds and supports a $57 million brine shrimp industry…

Mike Styler, who recently retired as executive director of the Utah Department of Natural Resources, said maintaining the viability of the Great Salt Lake will be one of the critical challenges the state faces going into the future.

He stressed that as agricultural water gets converted for urban use in Weber and Davis counties and reuse of waste water becomes more popular, that threatens to dry up marshes and wetlands that support the lake.

The Great Salt Lake has an average depth of 16 feet, covers 1,700 square miles during an average year and is two to seven times saltier than the ocean.

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