Thirty years of scientific study on a Vilas County lake will come to an end on Monday.
Scientists are removing a barrier that has divided Little Rock Lake in two since 1984. Researchers installed the barrier to conduct a landmark study on the effects of acid rain. Carl Watras is a research scientist with the state Department of Natural Resources. He's been involved with the Little Rock project since the beginning. Watras says at the time there was speculation about the effect of acid rain on lakes, but there was no definitive evidence.
“People were seeing declines in the fish population, the water clarity was increasing, there were dense growths of green filamentous algae on the bottom. And those were considered to be the signatures of acidification due to acid rain. But it hadn’t been proven.”
Thanks to the barrier in Little Rock lake, scientists have the proof. That proof was part of what spurred Congress to pass the Clean Air Act amendments that set limits on the sulfur dioxide emissions that contribute to acid rain. And Watras explains that building that barrier was critical to the success of the experiment.
“We wanted to make sure that we had a control – a reference basin that was as similar to the treated basin as it could be. And the best way to do that is to divide one lake in two.”
Little Rock was also the first lake where scientists demonstrated how mercury --transferred into lakes through rainfall—could accumulate in fish. Watras notes that though it’s the end of an era for the divided lake, it’s not the end of research at Little Rock.
“It’s just that there’s no need now for a treatment basin and a reference basin. WE can now remove the curtain, restore the lake to its natural condition, and still monitor the effects of changes in atmospheric deposition.”
Scientists will be removing the 250 foot plastic barrier on Monday.