And turning off Niagara Falls would shut down shipping as well.
1.5 million jobs in Michigan are connected to having the Great Lakes at a usable depth.
About 100,000 jobs are in bottled water.
You do the math.
Yup, I grew up on Lake St. Clair. In the 1970s they diked up the shoreline around my home because of anticipated high water levels flooding the suburbs of St. Clair Shores.
And turning off Niagara Falls would shut down shipping as well.
I've seen a lot of lake freighters in my day, and I've been to Niagara Falls a few times, but I can't once remember a freighter going either up or down the American or Horseshoe falls.
Shipping goes around the falls via the Welland Canal and its lock system. You can easily turn off the falls and still maintain shipping.
But the US and Canadian hydroelectric power plants use more water than Niagara Falls does. There is an international treaty between the US and Canada to limit the total waterflow down the Niagara River.
The biggest blow would be to tourism if the Falls were turned off permanently. They get turned down every night during the wintertime, and turned up during the day for the tourists.