Another case in point to illustrate this. A year ago, at the time of ice out, I noticed a very unusual lime green algae on the underside of the ice and the shallows were coated with it. We never had algae under the ice in the winter and it seemed an unusual amount of algae for the cold time of year.

Then after ice out and as water warmed up I battled algae like never before. As fast as I raked it out it came back. By mid summer it was nearly half of the pond. I worked repeatedly through summer and fall and it kept floating up from nowhere. Finally we ran out of 'nutrients' and water conditions switched and the algae just disappeared. I was stumped for most of the season to figure it out as nothing else changed with runoff or amount of feeding going on.

Then something clicked as to what may have been involved. The late summer before I wanted to improve aeration to the bottom of the pond. So I got a small plastic 'basstender' like dinghy and put a 6hp outboard motor on it. I waded into the shallows and my son was in the boat running the tiller of the motor. He would gun the engine which would force the boat into me. I would hold the front and then stabilize it while he would prop wash a big plume behind it. I would then rotate the front of the boat so his back end would go back and forth in a big arc blowing up huge plumes of leaves, dirt and debris. We would do each arc for 20 sec or so and then move over and do it again. It was hard work but we did that all the way around the pond over a few days.

I couldn't really measure the depth of muck before and after but I know we at least turned over a foot of the bottom debris out to a depth of about 6 feet all the way around. He then ripped around the pond perimeter in circles creating lots of wake and water movement till we had 'whitecaps' coming in the shallows.

Everything settle down and I didn't think about it much at all. I'm thinking now that I probably stirred up an immense amount of buried nutrients and therefore had a pretty intense algae bloom including in the winter and in the spring summer beyond that.

I hope that this spring/summer we'll have much less algae to deal with as hundreds of pounds of algae were carted into the woods. AT ice out this spring there was zero algae. Hopefully our nutrient load is less and yet someday we still will need a long arm excavator to come and truly excavate a couple feet of the bottom out to refresh the ecosystem.