By Howard Meyerson
Wildlife and fish habitat on the Boardman River was hit hard by a five foot deep surge of water on October 6 when a 20-foot draw-down of Brown Bridge Dam pond got out of control. State and other officials studying the aftermath say they do not anticipate any serious long-term fish or wildlife losses, but the six-hour flash flood did change some of the landscape.
“I am expecting some impact on wetlands, but those are going to be minimal. There was a natural floodplain downstream of the dam,” said Todd Kalish, the Michigan Department of Natural Resources representative on the Brown Bridge Dam implementation team.
“We don’t expect any impact on mammals along the river. There have been some stranded turtles that were rescued. Some fish were rescued too. There is a bald eagle out on Brown Bridge Pond that is still flying around having a field day (eating dead fish), the same with the otters and raccoons.”
Brown Bridge Dam is being removed to restore the natural flow in the upper Boardman River. It is the first of four dams that will either be removed or modified in an effort to restore the river to a more natural state. The draw-down was the first step in the dam deconstruction process.
Downstream fish and wildlife assessments are underway. Kalish and other officials say those results will be available in November.
Dead fish were prominent after the flood, according to Chuck Lombardo, the spokesman for the implementation team. Most, he said, were warm water species: bluegill, bass, pike and walleye.
“Most of those were fish from the pond which was warm water,” Lombardo said. “And as the river returned to being a cold water stream, those species wouldn’t have survived.
“We did get reports of dead trout being found and I have heard of a trout kill, but the results aren’t in yet.
“Our primary concern is the release of all that sediment and the impact that could have on the fishery.”
The amount of sediment lost has not been determined yet. What is known is that between 115,000 and 150,000 cubic yards were removed from the site prior to the breach, according to Lombardo. Another 25,000 cubic yards still has to be removed. Three feet of water still remains behind the dam and that will be removed once permits are issued from the Michigan Department of Environmental Quality.
Sand from the washout settled out in the upper half-mile immediately downstream of the dam, according to various officials, but fine silt suspended in the water is being carried much further downstream.
“The water is really turbid now and we can’t see the bottom,” said Steve Largent, the Boardman River Program Coordinator with the Grand Traverse Conservation District. “(During the event) I saw a cottontail rabbit on a person’s deck surrounded by water, but I think wildlife was able to take refuge quickly enough. I don’t think this was any different than any other big storm event.”
The surge of river water occurred during the draw-down Water began to flow around the temporary structure built to control the flow. The pond dropped approximately 17 feet in just six hours. The draw-down was to be limited to 12 inches per day for 18 to 20 days.
The flood pushed woody debris out of the river and into bridges and up on the floodplain, according Largent. That rise was similar to a 1986 flood from heavy rains, though the river came up slowly then.
“It could have been much worse,” Largent said.
Kalish, the DNR’s Lake Michigan basin coordinator said the sediment moving downstream may be good for the river habitat. It will introduce new organic material into areas that were “organically starved.”
“That material will be a benefit to cold-water fisheries,” Kalash said. “The material may boost aquatic insect populations.
“ I’ve walked down through there and saw a lot of the sand was deposited on the flood plain. In the river channel there is still gravel and good spawning habitat. I have a feeling we will see brown and brook trout populations there. Fish are already utilizing the river.
“I think our (trout) surveys will turn out to show very similar age classes of brown trout as in 2010. But I am not sure what it will show in terms of abundance.”
Copyright © 2012 Howard Meyerson