Lake weeds

[Waternut]

So the owner of our ski lake is draining his lake right now in hopes of freezing and killing the weeds. Since we'll have direct access to the weeds while it's down, can you guys recommend anything that would help prevent the weeds from taking over in the spring/summer when the water comes back up?

[A_B]

Blue dye. Sterile Amurs (carp).

[Waternut]

Chemicals and fish are hard to keep because this lake has a pretty steady flow of water going into it. The entire lake can be filled in about a week so that much water flows through the lake every week as well.

[Chef23]

You can cover the bottom with mats but that would be pricey.

[Golfguy]

Try a soil sterilant such as Diuron or any AG product used for ditch bank weed control. This will help for a while; because you have a flow through of water you may not be able to use diploid carp as there is a concern of downstream population. They are known to eliminate habitat for other desirable fish species. You did not say where the lake is. Watch the nutrient load in the lake and try to eliminate the source by diverting water inflow, or creating a pre lake settling pond with Cat tails to uptake the nutrients. Good luck.

[The_MS]

I would not be using Karmex (diuron) where you have run off or flow out. If the local EPA guys get wind, you will be up the creek.

[Waternut]

Hmmm...A settling pond sounds like a mosquito haven. This lake is in central GA. Never heard of trying to suck the nutrients out of the lake by planting stuff upstream. Wonder if it would work. Hard to say whether it's all weeds at the entrance to the lake that are depriving the weeds of nutrients at the end of the lake or whether an extra foot of water from 4 feet to 5 feet is making the difference but the end of the lake usually has fewer weeds.

 

The owner does spot spray diquat on the weeds that reach the surface but it doesn't do much to the weeds on the bottom. He has talked about laying black plastic with holes punched in it near the drop zones but I think it's just talk and not really a serious proposition.

[A_B]

That's what I was thinking OB, have some mesh fencing to keep Carp in.

[Dusty]

Of all the lakes here in NW, the grass carp are working best at weed control. Dye helps on top of them. At least around here, mosquitos are unable to live/breed in water over 18" deep. If there are viable fish species in that 18+ inches, you get an even better 'suppression' of the bugs. Could be other problems like snakes, alligators, turtles and muskrats though...

[liquid d]

put in the fish, and put a screen to stop them from getting out. Fish are the best!

[Intheday]

If you are lowering the lake level and have access to the weeds why not try a big dose of glyphosate? Not residual and relatively low toxicity contact only herbicide

[chris_logan]

This is entirely based on nutrients being washed in after rainfall and causing the growth: During inflow, is the water very muddy? If so, putting in a series of check dams upstream would clear up the inflow significantly. Depending on your budget, you may also want to look at placing floc logs in the upstream area to get the suspended particles to drop out. Water quality will improve significantly and will not hinder grass carp if you choose to go that route as well.

[boarditup]

Install and maintain a series of check dams (limestone rock with fabric underneath) to create a series of ponds in the inflow of the lake and somewhat raise the pH. This will reduce the sediment and nutrient loading of the lake. Dig deeper. The deeper the lake, the fewer the weeds. While you are at it, make sure the shallow areas have largely sterile bottoms - large grain sand or rocks. Silt and clay are ideal bottoms for weeds. Copper sulfate will prevent or stunt the growth of most weeds. It will last a while, but needs to be refreshed.

 

Glyphosate (Round Up) works best if mixed with sand to get it to the bottom. It does not last long - it is just a contact treatment. Use early to prevent growth. If you wait until the weeds grow and then kill them the decaying plant matter becomes nutrients for the next generation. So, remove as much as you can.

 

In general, the more you prevent nutrients from getting into the lake, the better off you are. Deeper water supports less plant life. Sand and rock bottoms are harder for plants to grow into than silts or clay.

[EricKelley]

Karl,

Tell us more about the recipe and use of the sand/roundup mix. Thanks

[epyscs]

Shit guys - look up some of the research on roundup and brain issues. Major links between that stuff and thinks like dementia, parkinsons, altzheimers. May only be low doses, but I would pass on lakes with the stuff in.

[eleeski]

@epycys There are so many risks we face in life. Worrying about a politically fueled controversy is misguided. Roundup has been around for years. Safe as salt water? No. But Michael J Fox probably never touched Roundup. Drug use, well...

 

However, Roundup on the cattails started my weed problem. It killed the plankton, made my water beautifully clear and let the Chara (pondweed) get established. Delicate balances.

 

I need to buy a weed harvester. Mechanically deal with the problem.

 

I tried to get @Horton's wife to grow bugs on my pondweed but they liked the garlic better. At least the bugs will taste better.

 

Eric

[Zman]

Harvesters look cool. Looked into that last year...but the big downside is the harvesting will spread more seeds and our weed continues to grow flowers and seed even broken free and floating. So, harvesting is just an expensive short term fix. In very serious situations, might still be a first step before herbicides and grass carp.

[Waternut]

I've seriously considered the Y shaped weed shear or weed razer that you just toss in the water and pull it back. Wouldn't work for the entire lake but if you can keep most of the weeds on the surface in check then that cutter could clear the drop zones which is honestly our biggest problem. If we start having problem again this year, I may see if I can just "mow" the weeds every few weeks with that cutter. I can't see it taking more than 30 minutes to clear each drop zone.

[liquid d]

with that much outflow, it should take the cut stuff right on out.

[Waternut]

Nah I'd have to drag it out once it's been cut or wait a couple days and let the wind do it's magic. We have a lot of outflow but the lake doesn't have a current.

[scuppers]

OB is right! Cutting underwater weeds is a disaster. Spreads it and makes it worse.

[Marco]

Carp and dye work wonders. Shortly after we built our lake, the weeds were so bad you couldn't swim across it. We initially treated the weeds with an aquacide, then put in grass carp and dye the lake. Problem solved. As the carp age and get bigger, their metabolism slows and they eat less (even though they are huge), so it is important to put in a few young ones every few years. We usually add 10 or 15 in our 9 acre lake every few years.

[eleeski]

@OB A thousand cormorants (seriously!) descended on my lake last week. I doubt I have a single fish left in the lake now. They cleaned out my entire crop of fish when I was fish farming in a day. We got a reprieve when West Nile and Avian Botulism decimated the cormorant populations but they seem to have rebounded quite well.

 

Fish are not a sure thing.

 

Eric