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Harrison Township — An unknown frozen black substance found this week on a seawall off Lake St. Clair is being tested to ascertain whether it is harmful, Macomb County officials said.

Samples of the smelly substance were taken by Macomb County Health Department officials to test for E. coli and other unknown materials to see if it is detrimental to human health.

"We don't really know if it's harmful, but we don't think so," said Candice Miller, the Macomb County public works commissioner, who has seen the substance up close. "I think what we will likely find is that it's organic material which is at the bottom of the lake that was churned up."

Miller said she thought it is likely the organic material was "fed" by "combined sewer overflows that have been going on for decades" from the Clinton River and the Clinton River spillway.

County health officials said they could have an answer as early as Thursday on what the substance is that was found in Harrison Township.

Harrison Township resident Joe Solomon, who lives long the lake, said he had never seen such a substance before.

"When we first moved in here 25 years ago, we had a beautiful beach," Solomon said. "Now, I haven't been able to use it for eight years" because of naturally occurring algae.

Jim Nash, water resources commissioner in Oakland County, said he doesn't believe this is sewer runoff from Oakland County, It is likely "lake turnover," a collection of weeds and other vegetation that die off, rise into the water, and get churned up by high winds and other storms, he said.

"The ice covers it and once that happens, everything is kind of still and it rots away," Nash said. "This is rotting vegetation mostly. If this had come from our sources, there would have been a trail of it all down the rivers right into the lake and you would have seen it. And you don't see that."

But a sewage overflow problem remains, Miller said. Whatever the substance turns out to be, she said, "it's certainly nothing that you would want in your back yard frozen on the seawalls."

lfleming@detroitnews.com

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