By Zach Jay
The Mining Journal (Marquette)
ISHPEMING, Mich. (AP) - Ishpeming's Lake Bancroft is becoming a bog.
Or it would be, anyway, if not for the efforts of the Lake Bancroft Committee over the past three years.
The committee saw the sum of its efforts go into action last week, starting a pump which pushes the lake's water through bricks of a water-soluble, environmentally safe polymer which binds - or "flocculates" - with the suspended sediment filling the lake, according to The Mining Journal of Marquette.
The sediment, which could just as accurately (or perhaps more accurately) be called "muck" or "goop" or "crud," is made of decayed organic matter. Rich in phosphates and nitrates, the sediment consists mostly of dead vegetation, delectable fare for exactly the kind of weeds, algae and bacteria contributing to the water's eutrophication - the process turning the lake into a bog in the first place.
The polymer, described on Atlanta-based Applied Polymer Systems' website as an "anionic polyacrylamide product," was created by the president of APS, Steve Iwinski, who now lives in Big Bay.
Iwinski himself has volunteered to help with the committee's efforts, coming weekly to collect water samples for analysis.
To implement use of the polymer in Lake Bancroft, a pump, fixed to a pair of rusty barrels afloat some 30 feet out, feeds water down a six-inch red hose loaned to the committee by Ishpeming contractor A. Lindberg & Sons, through three metal canisters containing the spongy blue bricks of polymer, then back through a length of hose on the far end, where it's deposited back into the lake.
"We put the blocks of polymer in the treatment unit and as we pump the water through it, the polymer gets dissolved in the water and then we pump it back into the lake," said Carr Baldwin, who, in addition to being a committee member, offers the group what he called "technical support" as a professional engineer with a master's degree in sanitary engineering.
By binding to the fine particles suspended in the water, the polymer allows them to sink to the bottom of the lake, while also preventing the phosphates in the sediment from being used by the lake's plants and algae, thus slowing their growth rate.
"...If we're successful, we'll increase the depth of clear water in there and compact and compress the stuff that's now suspended in the middle of the water column there," Baldwin said. "This polymer treatment should, like I say, clarify the water quite a bit. The organic material's still in the lake; it's not going anyplace. We're just trying to compress it down so that it occupies much less space. I guess the ultimate solution would be to get in there with some type of a dredging unit and pump all that stuff out of the lake, but that's a very expensive process. This process is quite cheap, comparatively."
Baldwin said the cost to use the polymer bricks, which are about $250 apiece, is roughly $3,000 per week, plus electricity to run the pump. Luckily, the committee has gotten a lot of community support, including about $4,000 from individuals and more than $20,000 from area businesses and service organizations - $10,000 of which came from Cliffs Natural Resources.
Lake Bancroft's natural bottom, Baldwin said, is about 25 feet deep, but right now has an "apparent bottom" of about three feet. That's created problems with another necessary step in improving the lake's ecosystem - aerating, or adding oxygen to, the water.
"When the city had the fountains in there, that was aerating the lake and it helped control things, but we had a series of dry weather, dry summers, and the lake level dropped some and the fountains got into that goop - I don't know what the technical word is - and would plug up," Baldwin said. "And so then ... when that happened, a lot of times the (fountain) motor would have to be rebuilt afterward, and it got to be a serious maintenance problem for the lake."
Baldwin said aerating the lake allows aerobic bacteria - those that thrive in an oxygen-rich environment - to break down the organic matter filling the lake. That's important, he said, because aerobic bacteria work about 10 times faster than the anaerobic bacteria working on the sediment where oxygen levels are low.
Part of the battle to rehabilitate the lake into an environment where fish and healthy aquatic plants can thrive stems from the fact that it has no in or outlets.
"All its water is from groundwater that seeps in around it, you know, and there's no stream flowing into it and there's no stream flowing out of it, so there's never any flushing action," Baldwin said. "If you take Deer Lake or Teal Lake, there's flow through those lakes, and so you get a turnover, a change of stuff."
With no way to refresh the water or remove the sediment, without human intervention it's only a matter of time until the lake becomes a bog.
"It's a normal process ... if you go out in the woods around here, you'll find these bogs that, some of 'em you can walk across now, some of 'em just have a few frogs in 'em and stuff, and they eventually fill up with this organic material and become a peat bog," Baldwin said. "And that's what the natural course of events would be for Lake Bancroft. You know, when I think of somebody, say, approximately 100 years ago was able to catch walleye in that lake, and now minnows can't even live through the winter, generally, because there's not enough oxygen in there."
To Mike Tonkin, a city councilman and committee member, the use of the polymer is absolutely necessary to stop the eutrophication process.
"If we let it go, it's just going to be one big, stinking mud hole," he said. "Literally, yeah. And I don't think you'd want that in the middle of your city, wouldja?"
Published: Thu, Sep 11, 2014
