lake levels

Ben Meyer/WXPR

Are the Northwoods walleye you catch safe to eat, or do they have too much mercury?

The answer is tied to several factors, but new research shows a surprising variable might have the biggest effect.

The water level of the lake where you caught the fish could tell you more about its safety than anything else.

The realization of the connection started years ago, when lakes researcher Dr. Carl Watras found an interesting trend.

Ben Meyer/WXPR

Records of water levels on many Northwoods lakes often only go back a few decades, if they exist at all.

But one researcher has figured out a way to see the story of lakes going back hundreds of years.

That history, and a clue about the future, is as simple as tree rings themselves.

“We’re proposing using these trees as an Excel spreadsheet, as a way to get at [the history of] these lake levels,” said Dom Ciruzzi, a UW-Madison graduate student working at Trout Lake Station in Boulder Junction.