aunt betty wrote:That's the one. They poison the milfoil at that Rantoul pond. They've been piddling with trying to come up with some sort of algorithm to tell them how much poison to use. Been at it for 25 or 30 years and they still can't figure out how to control weeds in a pond.
There are two ways to "control" it.
Fluridone, but that kills almost every weed in the pond. It comes in jugs, and you simply dump it in the prop wash of a boat as you motor around the pond. This only works if you don't have a large inflow/outflow otherwise it becomes diluted too quickly. There is a certain ppm target for milfoil. That doesn't kill lily pads and some good natural species, but most things will be dead. If you have a lot a nutrients in your pond, lots of sediment on the body, you WILL get algae blooms. And 2 to 3 years later, you are back to square one. Our one pond has too damned many common carp in it, but by keeping the pond cloudy, we get 3-4 years out of a fluridone treatment. This is the "cheap" method. We spend $10k-$20k per year on this
In addition, to the algae, you have now eliminated all the cover for the little fish, so the big fish eat very well for a year or two. So you don't want to do this every year or you won't have a healthy fish population. So we let a lake choke up with weeds, listen to our members bitch, and then we repeat. We have 5 very large lakes, so we treat one or two every year, so there always lakes that are wide open to completely choked with weeds, but some members want their favorite lake perfect every year. which leads to the second and expensive approach.
Dies, what the common carp do and why common carp are such a nuisance, are useful to slow weed growth and control algae. They are a small help that we often use in our kids pond, because we want that fishable every year, so we fluridone it more often, add die, and then we supplemental stock it to keep the fish population up.
I don't remember the chemical, but you can spot treat a lake and kill things locally, leave nice weed edges, boat lanes, ... You can really manicure your lake. And if we were willing to spend $100k per year on just weed control we could do that. We only use that when we have really dry years or to address problems and then only very sparingly to keep certain shore fishing areas and boat lanes open.
Grass carp were a popular approach, but you do one of two things. Not enough carp and the weeds are not controlled at all. Too many grass carp, and your pond is completely weed free and unhealthy for a decade until the carp start dying. If you want 50 lb fish to shoot with your bow, stock some grass carp. To control weeds, nope. We put too many in our one lake and it was really screwed for a long time. Most are now gone, but their are some giants. I saw several in the 50 lb range about a month ago when I was out, but never got close enough to shoot one. I did get a 52 lber (giver or take 10% on the cheap scale) a while ago. Many do they fight, even when shot with a bow. But they are terrible for weed control.
We are having a trial run on some treatments to consume the muck. The weed problem gets worse each year. All the nutrients that enter don't leave. So when you kill the weeds, the nutrients settle to the bottom and then new nutrients enter, so the weeds grow more aggressively each year. Getting the nutrients out of the system is very expensive. It will be a big help in slowing weed growth. Decades of accumulation of nutrients in the sediment add up. We are trying these treatment that use microorganisms that actually consume the muck and get a lot of nutrients out of the system. If it works, it's more money, but it will open up areas where the muck is nearly to the surface so you can't get back there, plus are useless for fish spawning and just support weed growth.
Dredging as noted by others, where do you put the spoils? If you want channels, you can make some areas deeper, but other areas will be shallower. We are in the 100 year flood plane, so we can't dump them on land if we wanted to. 30 years ago, our club was fined for doing just that. They were creating a deep hole in a relatively shallow lake so the walleyes and other fish had somewhere to go in the heat. Now we have aerators and big electric bills. Many strategically placed near duck blinds to keep them open
It's actually not hard. It's just expensive. What do you want and what are you willing to spend? Our annual club budget is $100k/yr. A caretaker, roads, docks, aerators, buildings, equipment, fish stocking, lawns, brush control, improvements, ... There are a lot of other expenses We could easily spend the entire budget on weed treatment if we wanted a manicured club. Nuke it with fluridone let it weed back up and nuke it again works well when you have 5 lakes. If you have just one, having it almost unfishable in the summer 2 out 5 years is not. Nuking it every other year also doesn't work unless you want to stock adult fish or have a whole lot more structure than most lakes.