Pond Boss Forums POND CONSTRUCTION Building a dam Big dam holes to fill?

Another project to add to the list!

Knowing there was a leak of about 2" per week, I decided to let it go to see if it would stop, and where.

It's now either stopped or really slowed, so out in the boat I went and found too many of what you see below as well as smaller ones too, likely from muskrats. The bigger ones I'm guessing are from beaver? But I've been here a year and have seen no signs at all. Just muskrats that I'm trying to control.

As it's not in an area where I can pack clay, would bentonite be a viable option? I also saw someone mention bags of cement but I don't know if that was just to deter a beaver, or if it might be effective as a sealer (somewhat). It just doesn't seem like a good idea.

Any ideas or suggestions on filling these holes? At full pool the bottom of the hole is just below the water line.

The first pic is the dam where most of the holes are, and it's the deepest area of the pond.

I have had this often at my ponds. I have a wetlands along my ponds so there are always muskrats around. What I do is dump in clay if you can to plug the hole. Then lay in a peice of chain link fence over the area, this will keep them out. You'll know its working when you see notice muskrats with really short teeth from chewing on steel! But seriously it does work, I have chain link buried in my entire Dam.

Thanks for the reply Woodster,

Getting clay to the big holes let alone packing it in just doesn't seem to be an option for where the holes are located, and until I see ANY sign of a beaver I really think the holes are from the past, if they were caused by beaver.

I read elsewhere about mixing dirt and ready-mix bags of concrete and tossing that in the holes but I'm still leary about the idea unless it's been successful for others. I just don't know chemically if there's anything in the concrete that would "taint" the water.

If I can locate bentonite I guess I'll give that a shot.

I've had to turn the well back on to bring the water level up so I need to do something soon.

Any other suggestioins or ideas? I'm not getting much feedback on this one

If it is an old beaver den you might have to bring in some equipment and pack the tunnel, the tunnel might be more extensive than you think. We had a beaver tunnel into the dam at my dad's old pond once and during some heavy rains and high water it broke through the backside of the dam when the tunnel flooded. The 30" tunnel went into the dam 15ft then "T"ed off another 30ft in both directions parallel to the dam. Look for a small air hole up above entrance, this is where it might "T" if it is a an old beaver den.

Thanks Shorty and you're right about not knowing what's in the hole, where it goes, how far it goes and if it leads to a bigger den (and bigger hole weakening the ground on top).

There are air holes up above that I have filled in and they have not been reopened or new ones shown up, which again makes me think these are existing holes at the water line. And by the way, the two holes in the pictures are a good 50-75' apart.

I don't have a "backside" to the dam as the ground is level at the top of the dam for a few hundred feet back. Not sure what kind of dam that's called but it's not a typical built-up dam (very old pond!)

I'm guessing that the water may just be seeping into the soil so if I can slow it down or stop it, I've gained something. Once I get some bentonite in there I will do what I can to fill the holes as much as possible. Even possibly a post-hole digger to access the den and have a way of filling it all up. A lot of things "depend" on doing that though.

Thanks again!

Ll, the post hole digger at the air holes sounds like a good idea, and then fill with a mixture of clay and bentonite. Good luck...

It has been so dry here for what seems like forever the ground around your pond may just be "soaking in" like a new pond would. You might not have a leak at all, just a hole.

Muskrats for sure. They are digging into the bank to eat the roots of the grass. In the second picture see on the right that small mound? They are sitting there cleaning their self after digging and feeding.

If your allowed to use leg hole traps set one right there with a hunk of parsnip on it. In the spring time like now if you have any apple trees in the pond area there will be very high traffic there too.

Those banks will just cave in and should not go back in to far unless they are using them for a den.

Trap them now before they re populate this spring and it will be in this month.

Cheers Don.

P.S. I really don't think there is any beavers there. You will have a feed bed of young yellow birch or poplar tops stacked in front of these dens.

Thanks, everyone for the input and continuing education!

Shorty, I know what you're saying about being so dry here but I'm fortunate to have kept my pond from going down with having a well to have kept it at a consistent level. It was just recently I decided to let it go down to ascertain where the leak might be before the heat of the summer (and evaporation) kicks in.

I took the boat out yesterday and got a good close look at those holes, one my buddy could have crawled in but wouldn't . Wow, it's incredible how big and deep they are! My water level is coming back up and just reaching the bottom of the holes, allowing water in. This is where I think it may be seeping into the soil (compromised liner).

I'm at the thought of the post-hole digger if I can make it through the roots for the one in the third picture as there's very dense brush in the area, so hopefully there's an air hole I can use for access. The others I think I can open up enough to fill,,, hopefully!

Regarding the traps, I have leg-hold and conibears that I've tried putting in the muskrat runs but they've done a good job of avoiding them! So, I'll continue trying to trap/eliminate the "rats" and I'll try the parsnip idea. Although I do have mink in the area and was told they could control 2-3 muskrats per month.

I'm also not having much luck on finding bentonite

Thanks again everyone!

PB Rocks!

If the holes are much bigger than 8" they were made by beaver.

See worst case the beaver will dig into the bank but even then there should be a feed bed of tree tops right in front of the dens.

I know big cat fish will dig the bank out like that but the water level would have to be up much higher.

I nice conibear will do the trick. Make sure it is in the path they are making. You do need to mount it 1/2 to 1" under the water level and place a stick at the water level right above the trap. When they swim along their path on the surface as they get to the stick they will duck under the stick and go down into the trap. Wap. No stick they will not duck into the trap.

Cheers Don.

Esshup, then I'm sure they're beaver holes, especially with each of them having air holes. I just think they're old ones. No evidence that they're around any more.

Don, thanks for the tips & info on trapping! And back in the day there very well could have been some big cats in there.

Hope you all had a nice weekend, here near Lincoln we had beautiful weather in the 70's.. Now hoping for the rain they're calling for over the next few days!