BOULDER, Colo. -- Boulder County road crews used heavy maintainers to grade over several washed out roads near Nederland Thursday.

A big thunderstorm the night before left 8 inches of hail on the ground and washed out several roads and driveways.

It also caused at least one mudslide.

Lisa Olds returned home from work Wednesday and noticed that several deep gullies had been carved alongside her driveway. The biggest was nearly 4 feet deep.

“I was shocked,” Olds told 7NEWS. “I’ve been here for 21 years and in July, this is the worst I’ve seen it.”

Olds said the washed out gullies made for a nerve wracking drive up to her house. But she said those gullies were nothing compared to what she found once she pulled up to her front door.

“There was a mudslide,” she said. “It came right down the hill and just buried the whole back corner of the house.”

Olds said she doesn’t know if the 3 feet of mud knocked the home off its foundation, but she said the goo didn’t come inside.

While heavy rain and hail were falling in Nederland, the Office of Emergency Management in Boulder was keeping watch on the sky and on weather radar.

“We know that Boulder is vulnerable to flash flood types of scenarios,” said Sgt. Dan Barber of the OEM.

Barber said that whenever a major storm develops in the mountains west of Boulder and the city escapes flooding there is a sense that they dodged a bullet.

Barber said they weren’t too worried about flooding Wednesday because the storm occurred in an area west of Barker and Gross reservoirs.

“Those reservoirs could have handled the inflow,” Barber said.

Barber added that both Boulder and Boulder County work together the National Weather Service and the Urban Flood Control and Drainage district to monitor weather conditions in the high country and on the plains.

“We have rain gauges, stream gauges and a siren system to monitor conditions and to warn residents of danger,” Barber told 7NEWS.

“The message we want to get out to residents is if you hear the siren, that’s a clue to take some kind of action,” Barber added. “If it’s a flood, go to high ground. If it’s a tornado, go to a shelter.”