#Runoff news: Tenmile Creek, Straight Creek and the Snake River all approaching flood levels

From The Summit Daily (Deepan Dutta):

The water is roaring across Summit County. Tenmile Creek, Straight Creek and the Snake River are all approaching flood levels as the great 2019 spring runoff rushes in with thunderstorms on the way this weekend…

Tenmile Creek is one of the best gauges of how powerful the runoff is. The stream is currently cresting at 3.88 feet, with overflows into low-lying areas in and west of Frisco beginning at 4.8 feet…

At 5 feet, Tenmile Creek is at flood stage. At that point, there will be minor flooding of roads and properties along Tenmile Creek. At 6.5 feet, or moderate flood stage, houses begin to flood. Major flood stage starts at 7.5 feet, with significant flooding in Frisco and on the westbound lane of Interstate 70.

Residents should take some comfort in knowing that Tenmile Creek never has gone above 5.14 feet, a mark set June 17, 1995. Frisco authorities have continued to warn residents about potential flooding, with town and county staff on standby in case banks get run over.

The Snake River is currently sitting at 2.7 feet, with flood mitigation action called for at 3.3 feet. The Snake’s record crest was set June 6, 1972, when it reached 3.88 feet. At 3.8 feet, Keystone begins to flood, but that level has been reached only twice since record keeping began there in the 1940s.

Straight Creek in Dillon is currently at 4.86 feet, with action stage at 5.3 feet and flood stage at 6 feet. That stage never has been reached in recorded history, with Straight Creek topping out at 5.78 feet June 17, 1995.

Water flows into and out of local reservoirs also are rapidly speeding up. On Friday, Green Mountain Reservoir started ramping up outflows into the Blue River. Starting at 800 cubic feet per second, the reservoir will increase flows by 50 cfs every two hours until it reaches 1,400 cfs at 4 a.m. Saturday. That flow will be maintained until further notice.

The increased flows are meant to support the Coordinated Reservoir Operations initiative which seeks to enhance spring water flows consistent with the Upper Colorado River Endangered Fish Recovery Program. The conservation program seeks to boost the number of humpack chub, razorback sucker, bonytail and Colorado pikeminnow populations in the Blue.

Further south, the Dillon Reservoir is rapidly filling up after space was made for runoff these past few weeks. Water is dumping into the reservoir at a rate of more than 2,100 cfs, with outflows into the Blue River under the dam reaching up to 700 cfs. The reservoir is currently 83% full and just 15 feet shy of reaching peak elevation.

From The Moab Times-Independent (Carter Pape):

Based on historical averages, the Colorado River typically peaks near Moab during the first week of June. This year the river is projected to peak later; a forecast from the National Weather Service showed the river could reach its maximum on June 15.

Regardless of whether the peak is already behind, the river is high this year. On Monday, June 10, the United States Geological survey measured nearly 40,000 cubic feet of water per second flowing through the Colorado near Cisco, roughly twice the average for this time of year. The National Weather Service has issued a flood advisory for the Colorado River near the Utah/Colorado state line in Mesa and Grand counties…

Farther upstream, the National Weather Service issued a flood advisory on June 11 between Grand Junction and the Utah state line as a result of the river nearing flood levels that morning.“ Minor low land flooding is expected with impacts along recreation trails already being experienced,” the Weather Service said in its flood advisory statement. “Water levels and flows along the Colorado River in Mesa and Grand counties will continue to increase due to the recent warm trend. River levels will stay high through the week…The water is swift, [it is] cold and contains debris and snags. Know your limits if recreating on or near the Colorado. A life jacket and proper equipment is a must. Smaller tributaries in the area are also running fast and cold.”

Down the river, the water has been higher than typical, but not a danger to areas in the floodplain. At its peak, the U.S. Geological Survey gauged the height of the river near Cisco to be over 14 feet this week…

Local Colorado River tributaries are also higher than typical for this time of year. Near the head of the Dolores River, the USGS measured the location’s highest instantaneous flow since 1987 at 4,360 cfs.

At Mill Creek, before the Sheley Diversion that flows into Ken’s Lake, a gauge measured an average flow rate of 88 cfs on June 8, three times the daily average for the same time of year.

As high as the waters may seem this week, they are far from a record for the area, which had much heavier flows historically due to a lack of damming upstream. In one day in 1884, more water flowed past Moab than the city has used since January 2000.

According to the USGS, the highest flow rate on record for the Colorado River at the gauging location near Cisco, just after the Dolores River junction, was measured on July 4, 1884. The flow rate that Independence Day was measured to be 125,000 cfs.

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