#Runoff/#Snowpack news: Dolores is sizing up snowmelt flooding potential

Dolores

From The Cortez Journal (Jim Mimiaga):

On Monday, 30 officials and residents attended an informational meeting at the Dolores Fire Station hosted by Montezuma County emergency manager Mike Pasquin.

The town has not experienced a major flood from the river since 1911, which filled the town valley with up to 3 feet of water.

But there is potential this year because of the heavy snowpack, warming weather, and wet El Niño weather pattern.

The Dolores River peaks from snowmelt between May 15 and June 15, officials said. How much comes down and at what rate depends on snowpack levels, temperature, rain and soil moisture. Runoff forecasting is an educated guess, and possible flood levels require ground truthing as well.

There are some trigger points to watch for, officials said.

Flood stage for the Dolores River in town is 8 feet. A safe maximum flow of the Dolores River is about 6,000 cubic feet per second in town, said Ken Curtis of the Dolores Water Conservancy District.

Flows above that increases the risk of flooding, and flows of 7,000 or 8,000 cfs would start to overflow the banks. Flows can be viewed by visiting the Dolores River Boating Advocates web page

Increased flows from a hot spell or rain event in the upper valley takes time to reach town and usually arrives at night, said town board member Val Truelsen, “so there should be some nighttime monitoring of the banks.”

Residents should stay tuned to the National Weather Service for regional and local flood watches and warnings.

Montezuma County Sheriff Steve Nowlin said the community will be given warnings about predicted flooding conditions through media outlets, town reports, reverse 911, Nixle and social media. The town has recently repaired emergency siren that would also be activated as a warning.

Bridges up the valley are being monitored for debris accumulation and to ensure boaters can safely get under them. Collapsed mines in Rico that collect runoff have automated sensors that warn emergency personnel if the pressure and levels are too high, triggering relief valves.

Community sandbagging projects are happening in some flood-prone towns in the state, said Karen Dixon, emergency manager for the county health department. Local agencies said they are ready to respond to a flood emergency with equipment and staff.

If needed, sand is available at the county shop on County Road 30, said county road manager Rob Englehart.

Officials said severe flooding could compromise utility systems such as water, sewer and natural gas lines, and cause them to be shut down until the water recedes and repairs are made.

Potential shelter areas for evacuees discussed were the Dolores Community Center, Dolores High School, county fairgrounds, House Creek and McPhee campgrounds, and Canyons of the Ancients Museum and Visitor’s Center.

Westwide SNOTEL basin-filled map April 16, 2019 via the NRCS.

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