Dam Failure Causes Major Flooding

Dam Failure Causes Major Flooding

By: Scott McEwen

 

On Tuesday, May 13th, high water from the previous weekend’s rainstorms knocked out a bridge over Boise Creek in Michigan’s Upper Peninsula, due north of the Dead River Basin, near the City of Marquette, and not far from Lake Superior. Two days later, an earthen dike at the dam on Silver Lake Basin also burst, causing massive flooding downstream on the Dead River. About 9 billion gallons of water rushed down the Dead River toward the Hoist Basin, 15 miles away. Nearly 2,000 area residents in the Marquette area were evacuated for safety reasons, including the fear that the Hoist Dam (built in 1916) might fail because the Dead River Basin was now at a critical flood stage. Area roads were flooded and impassable and floodwaters were spreading out toward populated areas.

The environmental damage done to forest areas and fisheries due to dam failure has been extreme. Trees, logs, railroad ties, and other flood debris had made its way into Lake Superior by early the next day. Erosion damage will be one of the main problems for the watershed’s recovery. “We have a 25-mile swath of erosion starting at the Silver Lake Basin, so there will be countless erosion sites as the water levels drop”, said Carl Lindquist of the Central Lake Superior Watershed Partnership. He added that the main concern around the erosion sites would be sedimentation, with the rushing water dragging and pushing rock, dirt, and other debris along with it as it rushes toward Lake Superior.The sedimentation will cover the aquatic habitat for fish, aquatic insects, and other water-dependent wildlife. Over 130,000 Chinook salmon being raised by the DNR have died due to a lack of oxygen from the silt and debris. A silt line was clearly visible 1,000 yards off shore in Marquette Bay within 24 hours of the initial dike failure.

The cleanup work and repairs will be massive. Several bridges are out and many roads flooded. A natural gas line ruptured, and water and sanitary sewer mains needed to be shut off to facilitate repairs. On May 16th, Governor Jennifer Granholm declared a State of Emergency for Marquette County. The Natural Resources Conservation Service has identified nine sites in Marquette County that require immediate stabilization. Initial estimates of flood damage are $100 million. So who or what was at fault? Surely dikes should be able to handle a heavy rain occasionally. Was there a structural problem with the dike? Had it been inspected recently? Have the other, mostly very old, dams downstream been inspected routinely? Has the cumulative effect of a cascade of dam failures been assessed and an action plan put in place by local, state, and federal officials? Has thought been given to whether these dikes and dams really need to be there? There are no immediate answers to these questions, but many organizations will undoubtedly be searching for answers as the cleanup continues. For more information on this flood and/or to keep up-to-date on the restoration and cleanup efforts please visit:www.miningjournal.net.

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Images courtesy of Steven Huyser-Honig,
West Grand Boulevard Collaborative, & Yellow Dog Watershed Preserve.