The water level at the Cheboygan Lock and Dam Complex dropped slightly Monday as state officials were optimistic the dam has adequate safeguards against a breach, even though the Cheboygan River’s water level remained stubbornly high through the weekend.
The river was 7.68 inches below the top of the dam on Monday at 9:30 a.m., an improvement of 0.12 inches from the last reading at 10 p.m. Sunday. State officials said in a community update Sunday at the Cheboygan Opera House in Cheboygan that crews continue to pump hundreds of millions of gallons of water out of the dam each day.
Michelle Crook, a senior engineer with Michigan’s Department of Natural Resources, said modeling indicates flooding wouldn’t occur until water reaches at least a foot over the top of the dam because of sandbagging and other measures put in place to keep water at bay.
The agency has been calculating what it considers a worst-case scenario: Failures of the Alverno Dam, immediately upstream on the Black River, followed by the Cheboygan Dam.
“Not a very likely scenario. Alverno should not fail Cheboygan. But we wanted to play that scenario out to provide what those impacts are,” Crook said.
The public meeting was held to update communities on what was happening to ease the dam levels and what monitoring measures were in place.
The river’s fluctuating levels have had Cheboygan residents on edge since Friday, April 10. The level in the dam reached 18 inches below the top and triggered a state of emergency declaration Friday by Gov. Gretchen Whitmer.
The water moved to less than 5 inches from the top at its peak so far, but some relief came Friday with the restarting of a former hydroelectric dam at the Cheboygan Lock and Dam Complex that had been offline for three years. It has increased water passing through the dam up to 30% from putting the turbines back online.
Michigan State Police credited the turbines with a 2-inch drop in the river level by Friday afternoon.
Nate Stearns, the operations section chief for the DNR’s Cheboygan Dam incident management team, said Sunday that 17 pumps at the site have been pumping 188,500 gallons of water every minute around the spillway, amounting to more than 271 million gallons every 24 hours.
“This is a monumental pump operation that we’ve set up here at the boat launch,” Stearns said. “That’s, I think, saved our bacon here recently.”
The Cheboygan Dam is classified as a “high hazard” dam. The hazard classification is based on risks to life and property if the dam were to fail, not the condition of the dam. High-hazard dams undergo yearly inspections by the Federal Energy Regulatory Commission, said the agency’s director of dam safety, Dave Capka.
T Crews raced to clear debris and reinforce other dams close by. Levels have fluctuated around the 7-inch range below the top on Friday and Saturday. Authorities said Sunday they expect peak river flow in the next two days. Keeping the Black River moving is essential because it feeds into the Cheboygan River, officials say.
jcardi@detroitnews.com
This article originally appeared on The Detroit News: Cheboygan Dam’s water level drops slighty, but remains inches from top
Reporting by Julia Cardi, The Detroit News / The Detroit News
USA TODAY Network via Reuters Connect
