After rains swell Cascade Lake, pressuring dam, officials plan to release water downstream

Flooding closed a number of roads in Carroll County July 25, 2018.
Flooding closed a number of roads in Carroll County July 25, 2018. (Alex Mann/Carroll County Times)

After heavy rains overnight Friday filled Cascade Lake to the brim by Saturday morning, Carroll County officials cautioned that an uncontrolled breach of the lake’s dam, and thus further flooding, was possible.

However, because engineering crews were able to lower the water level significantly throughout the day, officials’ concern was lessened by the evening.


“It’s down about 1.5 to 2 feet today,” Carroll County Sheriff’s Office spokesman Timothy Brown said of the lake’s water level at about 6 p.m. Saturday.

Although crews continued to pump water from the lake Sunday, according to a Sunday evening news release from the Sheriff’s Office, a controlled breach of the dam is being planned tentatively for Monday morning. A controlled breach would allow more water to flow downstream, relieving water levels at the lake but risking flooding downstream.

“During excavation of the dam, there remains a hazard of a dam failure so area residents are advised to remain vigilant and aware,” the news release said.

In a Saturday morning news release, Brown said the overnight rains had both filled the lake and damaged the dam, such that people living along the tributary of the east branch of the Patapsco River should be ready for large volumes of flowing water and possible flooding, should a breach of the dam occur.

Snydersburg Road between Cape Horn Road and Hampstead Mexico Road/Md. 482 was closed to traffic due to the overflowing lake and potential for flooding, while reverse 911 calls and door-to-door visits were made to people living in downstream areas, according to Carroll County Sheriff Jim DeWees.

“Early on we were panicking a little bit, because it was really over the top and had exceeded the lake’s capacity, there were no two ways about it,” DeWees said. “But folks stepped up and were able to get additional pumping equipment out there.”

The heavy rains of the past two weeks had already filled Cascade Lake to its maximum capacity, damaging the dam, and as of July 30 workers were using pumps to divert water into the east branch of the Patapsco River, trying to reduce the level of water in the lake to allow for a safe, controlled breach of the dam.

That work had progressed well enough that a Carroll County government news release Friday night said the immediate threat of flooding was reduced and lake levels were then low enough for a controlled breach. “Plans for the dam breach were developed by the property owner’s engineers, and have been reviewed and approved by the Maryland Department of the Environment’s Division of Dam Safety,” the release said.

That plan was set back significantly — and, officials feared, permanently — as the most recent rains raised the possibility that the dam would breach on its own.

After bringing in an additional engineering company to pump more water from the lake and lower the water level Saturday, the plan for a controlled breach is now back on, tentatively for Monday, according to Brown. It depends on whether pumping can reduce the water level further by that time, he said, as it is still too high to engineer a controlled breach.

Larger barriers — basketball-sized boulders in clusters inside wire mesh — are also being placed downstream of the dam in order to slow the flow of water as it is released, both during the initial controlled breach, when it occurs, and for the future, according to DeWees.

Out of an abundance of caution, Brown said, law enforcement officers and road crews will remain in place to close down roads in the area that would be affected by an uncontrolled breach, should it occur, including:

  • Snydersburg Road and Cape Horn Road
  • Brodbeck Road by the Walmart
  • Brodbeck Road, Walmart side at #1517
  • Brillhart Road and Md. 482
  • Brodbeck Road and Schaeffer Drive
  • Md. 482 and North Brook
  • Shiloh Road and Brodbeck Road
  • Cape Horn Road and Brillhart Road
  • Harvey Gummel Road and N. Cape Horn Road
  • Md. 30 Bypass and Md. 482

Snydersburg Road between Cape Horn Road and Hampstead Mexico Road/Md. 482 has been and will remain closed, Brown said.

“We will have monitoring ’round the clock of the dam itself and we have resources in place to shut down those roads,” he said, noting the situation will be re-evaluated Sunday.