Water Quality and Improvement Projects

 

Lake Improvement Report  by Al Johnson

What an unusual year.  I can’t remember a year when we could sit around a campfire at 10:00 p.m. on the 4th of July weekend and not being eaten by mosquitoes–let alone not being bitten at all, even without spray.  We have also had very few days with green algae and I haven’t seen any blue green algae.  What else is unusual?  How about very little Curly-leaf pondweed (CLP)?  In fact, there were so little CLP that the weed cutting stopped early.

Before we delve into the absence of the CLP, let me report about our first vegetation survey of the year.  The survey apparatus is very simple: two tine rakes, welded back to back, without the handles.  The rake is thrown into the lake and retrieved.  The vegetation is then weighed and classified.  Last year, the rake was almost always full of vegetation.  This year, seldom did it come back up full.    We’ve been out twice in the last two weeks to conduct the survey in areas where we did: 1) chemical weed treatments; 2) mechanical treatment last year; 3) weed cutting; and 4) no treatment and no weed cutting.

The survey indicated basically no CLP in the area where we did chemical treatments, which is the way it should be.  The survey also showed that the rest of the entire lake had very little CLP, but the weeds we did find were equal amounts of CLP and Eurasian watermilfoil (EWM).
It was nice to see most of the rakes had at least some Elodea (Canadian water weed) and many with Chara (green algae), both of which are native to this area.  We will be conducting the vegetation surveys monthly to see if the amount of CLP or EWM change and if native plants will thrive with the reduced CLP.

Now I’d like to discuss why there is so little vegetation this year.  What has changed?  We know that the lake temperature this year was cooler later into this spring and summer.  Is this the cause?  We know it wasn’t due to excess snow this past winter, as there was no excess.  Or is it due to our weed cutting?  I would like to think weed cutting helps, but I doubt this is a factor as we don’t go that close to shore and the CLP turions (seeds) move with the current so they would move to areas that we don’t cut.   Some people would like to believe it is because of the carp.  Maybe they eat mosquitoes too!  The last survey in 2014 showed there were 0.92 carp per trap net compared to 3.75 carp per trap net in 1977.  The DNR would like to have the carp in the range of 0.22 to 1.02 carp per trap next.  Therefore, the amount of carp is within the desired range.

The DNR has seen years where the density of CLP is greatly reduced for no apparent reason.  This is observed frequently in nature where a species is greatly reduced compared to other years.   In short, we can’t pinpoint the cause and that is one of the reasons why we are doing the vegetation surveys.  Hopefully these surveys will continue for years, giving us good reliable data to make decisions on vegetation management.  Regardless of the cause for reduced CLP, we should enjoy it and make good use of our time at the lake.