We've got a 20 year old pond (2 acres) in northern Illinois. It's a rectangle. One of the long sides is a berm 15-20 feet wide. The berm leaks, particularly when the water is high in the pond. The biggest leak comes out the other side of the berm, ten fee or so down from the top of the berm. Trees have grown on the berm over the years and I assume it leaks along tree roots.

Not sure where to start or who to call for help. Would like to stop the leaks without attempting to rebuild the entire berm. Thought about digging a trench down the middle and repacking the soils there. Probably would have to remove the trees.

odds are its the trees that are making it leak. Your going to have to remove all of them and the stumps. They will just rot and cause more leaks. If you want to keep them...you could install a liner. Ive also read somewhere (I think on this website?) that there is a way to in inject cement in various places in the dam. You could also dredge the pond, and double up on your dam width. That might work as well. Benonite might be another option...but dont expect miracles from it.

Philblock,

I've renovated old ponds with trees on the dam just as you described and yes they leaked before renovation because of the tree roots and animal damage. There really isn't an easy way to fix this, that I know of, other than ripping out the trees and roots and then repacking the area in good clay.

Perhaps, as Face72 mentioned above, a liner would save you that expense but you would have to weight that cost against the cost of the liner and trade off the relative permanence of the dam repair fix vs the lifetime of a liner. I would not even consider bentonite for this kind of problem.

Brettski is a great fellow who is in your part of the country and frequents this site. Hopefully, he can recommend some local pond repair guys for your consideration. Good luck!

Philbock...
Welcome, my friend...always a pleasure to see another Illinoisan on the PB forum.
I am unable to offer specifics on dirt guys in northern Illinois. I will say, tho, that you will want to reach out to your county NRCS office and ask them. I worked the quad cities area a few years back, looking for my pond property, and the guys out there were extremely helpful and cooperative. Same thing in central Illinois. I have no experience with NRCS in northern Illinois, but it's worth a shot.

Thanks for the suggestions. I guess nothing's ever easy, right? I tried bentonite in the form of dumping a hundred or so bags of sodim bentonite kitty litter at the sites of the suspected leaks, to no success.