#Runoff/#Snowpack news: It looks like Blue Mesa Reservoir will fill this year

From The Grand Junction Daily Sentinel (Dennis Webb):

Aldis Strautins, hydrologist for the National Weather Service in Grand Junction, said so far snow has been melting off in a manageable fashion, with some minor flooding in lowland locations but nothing serious so far.

“We’re not totally out of the woods yet. It bears monitoring and keeping aware of the situation,” he said.

He said the Colorado River is coming up and may peak locally around Sunday. Andy Martsolf, emergency services director for the Mesa County Sheriff’s Office, said flows on the Colorado River at the state line are expected to peak at about 36,000 cubic feet per second this weekend. That’s up considerably from the 24,900 cfs being reported there by the U.S. Geological Survey Wednesday.

Officials expect a possible second peak later this month.

The Gunnison River already is cranking, but that’s by design, under the operational protocol for the Aspinall Unit dams on the river. Erik Knight, a hydrologist with the Bureau of Reclamation, said releases began on Saturday in an attempt to hit a target goal of flows of 14,350 cfs for 10 days on the lower Gunnison at Whitewater, to help critical habitat for endangered fish in that stretch.

He said it appears flows will fall 1,000 cfs short of that goal.

The National Weather Service has issued a flood advisory in the lower Gunnison River due to the extra water releases affecting river levels there. Strautins said it wasn’t a flood warning, but an effort to make people aware of dangers such as banks giving way due to the high water.

Knight said it doesn’t appear that flows through Delta will exceed 13,000 cfs during the 10-day release. That’s below the level at which the Bureau of Reclamation would cut back releases during the 10-day period to protect the community from flooding.

Wilma Erven, Delta’s parks, recreation and golf director, said some water is showing up in a park at the confluence of the Gunnison and Uncompahgre rivers, something that can occur in years like this one…

Strautins pointed to a mix of warmer and cooler weather in the forecast in coming days as opposed to a prolonged hot stretch that could drive water levels particularly high, with cloud cover also expected to moderate melting of snow.

Knight, who several months ago could hardly have imagined Blue Mesa Reservoir filling this year after last year’s low snowpack and drought, said it now appears almost certain to fill…

…the snowpack levels remaining in areas such as southwest Colorado are impressive, as evidenced by the mere fact that many sites that normally are dry by now still have snow.

According to one of the data sets [Brian] Domonkos uses, current snowpack levels in those combined basins and in the Gunnison basin are the second-highest on record, he said. But peak levels this year in basins in western Colorado don’t compare nearly as well to other high snowpack years, with the southwest Colorado basins ranking perhaps fourth or fifth, and other basins not coming in that high, Domonkos said.

He said one of his statistical tools indicates there are about 12.3 inches of snow water equivalent left in the Gunnison basin, which peaked at 24 inches.

“So we’re halfway through the melt of that peak snowpack,” he said.

The Colorado basin has about 11 inches of snow water equivalent left, after peaking at about 20 inches, Domonkos said.

He said snowpack normally melts at a rate of an inch a day or a little less of snow water equivalent.

“So snowpack on average probably won’t be hanging around too much longer,” he said.

While more than half of the Colorado basin’s snowpack already is melted, that snowpack was above-average, and Martsolf said the remaining snowpack is still about 71 percent of an average peak snowpack for the basin.

“We’re definitely melted off from where we would be for a seasonal peak but we still have a ways to go,” he said…

Nowhere in western Colorado is the combined threat of rising rivers and avalanche debris causing more concern than in Hinsdale County. Federal, state and county funding is paying the nearly $1 million cost for the ongoing, emergency removal of the historic, defunct Hidden Treasure Dam. While it no longer holds water, there’s concern that avalanche debris washing down Henson Creek combined with high water flows could destroy it, releasing water and debris and causing downstream flooding…

Both Henson and the Lake Fork of the Gunnison creeks pose threats to Lake City. Lyon said there’s currently no flooding occurring, but creek levels have come up considerably in recent days. Warming temperatures and possible rainstorms both could influence what ultimately occurs in coming days and weeks.

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