Flash flood watch in effect for parts of eastern Idaho due to erosion of Portneuf Dam Spillway
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CHESTERFIELD — A flash flood watch is in effect for Chesterfield and the surrounding communities.
The National Weather Service in Pocatello tells EastIdahoNews.com the flash flood watch is tied to concerns about the potential failure of the Portneuf Dam Spillway on the Chesterfield Reservoir.
The spillway is a side area where water flows out of the reservoir when the water gets high enough. Meteorologist Tim Axford says an “excessive” amount of water on the spillway is causing dirt and rock to scour out, which is causing some erosion. If it erodes to the point of failure, flooding could result in areas downstream of the reservoir.
“Failure of the spillway may result in flash flooding in low-lying areas below the dam, including areas that are already experiencing flooding along the Portneuf River,” according to the NWS.
The potential areas of impact include the Pebble area and communities along Old Highway 30 from Lava Hot Springs to McCammon.
Axford is urging people to stay away from areas in close proximity or immediately downstream of the spillway.
“County officials are certainly working on it right now to try and enforce the spillway. It’s not an immediate failure — we’re just trying to raise awareness for those in areas downstream of it to have a plan of action in case water does get higher,” Axford says.
The flash flood watch is in place until Friday afternoon. Officials will continue to monitor the situation. EastIdahoNews.com will provide updates once they’re available.
The latest road conditions and closures are available here. For a complete seven-day forecast, click here.
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