Natural Variation in L. Michigan Levels

[kgatesman]

In the article on reversing the Chicago River, it was noted that overtime the Lake might vary 6 feet in depth.

Is this why the (I believe WPA era) piers in Waukegan are perched ridiculously high above the boats? Once upon a time, did the boats rest comfortably against the slip fingers?

[Mr Downtown]

Probably (I've not seen the piers in question except on maps.live.com). Lake Michigan is near the bottom of what seems to be a roughly 30-year cycle, and hit record lows in 2007. Last year's snowy winter allowed a slight increase in 2008.

[Ed Zotti]

Originally Posted by Mr Downtown

Probably (I've not seen the piers in question except on maps.live.com). Lake Michigan is near the bottom of what seems to be a roughly 30-year cycle, and hit record lows in 2007. Last year's snowy winter allowed a slight increase in 2008.

I'd have to check, but the lake has certainly been a lot lower in the last few years - the beaches on the Michigan side for the past few years have been huge. Years ago (late 80s?) they were tiny. During the last low point, which I believe was in the 70s, the water was so low that it exposed the wooden pilings supporting much of the Chicago water edge infrastructure to air, allowing them to rot. This necessitated the expensive lakefront reconstruction project that's been underway for much of the past decade.

[Scruloose]

Originally Posted by kgatesman

In the article on reversing the Chicago River, it was noted that overtime the Lake might vary 6 feet in depth.

Is this why the (I believe WPA era) piers in Waukegan are perched ridiculously high above the boats? Once upon a time, did the boats rest comfortably against the slip fingers?

Yes, the lake level varies, and yes, that's why the piers in Waukegan look so high. As a Coastie currently working in the area, this issue is near and dear to my heart. When levels get low like they are now, my job becomes a pain in the ass. A lot of industry suffers as well, such as marinas like the one in Waukegan. The last time I was stationed on Lake Michigan, about 15 years ago, the lake levels were about 4-5 feet higher and all was right with the world. We had plenty of water everywhere we went and marinas didn't have to spend 20-30 thousand dollars a year to dredge out their entrances. Now? Ugh.

As Mr Downtown mentioned, the levels are cyclic. You can see the data (in meters) going back to 1860 here. Here's another look, this time in feet.

With the levels reaching record lows last year and the year before, there's been much speculation as to why this occurs and what helps the lakes recover. The one theory I hear most often blames the winters for the lake levels. When you have a very cold winter and little wind activity, you get more ice coverage on the lakes. The more ice coverage, the less evaporation into the cold, dry air. Tons of snow helps, too. But of the two, I'm told you'd rather have the ice. Heavy snow production usually comes from winter storms that brings lots of wind and wind keeps the water from freezing.

I've also read that we're diverting more water away from the lakes than we ever have before, and the lakes will never fully recover. We'll see. However, history shows that levels do rise and fall by as much as 6 feet. Plus, I just read somewhere that levels have been rising for the past 18 months, and we're about a foot higher than we were a year ago.