Residents in Lyons, Colorado are "completely isolated" by floodwaters that have disrupted their sewer and fresh water.
Boulder County Sheriff Joseph Pelle told 7News that residents were being told to reach for higher ground.
"They're completely isolated at this point. There is no access in or out," Pelle said during a Thursday media briefing. "They've lost their sewer plant, they've lost their fresh water, lost their market."
A notice from the National Weather Service around 2 a.m. reported an "overtopping" dam just about four miles west of Pinewood Springs, calling the situation "extremely dangerous."
Around 10 a.m. the Colorado Department of Public Health and Environment issued an order for Lyons residents to boil their water via Twitter:
— CDPHE (@CDPHE) September 12, 2013
Nearly all roads into Boulder have been cut off, and U.S. 36 was closed between Lyons and Estes Park Thursday.
A FOX31 reporter also tweeted that phone service is down in Estes Park:
— Chris Tomer (@chris_tomer) September 12, 2013
The NWS has issued a flash flood emergency for Boulder County and northwest Jefferson County until 10 p.m.
More photos from Colorado's flash flood below: