Pond Boss Forums POND CONSTRUCTION Building a dam Pond/Dam Issues

Hey all,

brand new member and really excited about finding this site. I am really looking forward to some good advice on my pond. I have about a two acre pond with a dam on one side that i have been told is too steep. The dam also has leaks caused by tree roots and musk rats. I have gotten rid of both. Problem is I am not sure what is the next best step to fix the dam. I have tried bentonite in those holes I see, with limited success. I have been told to: cut a strip down the center of the dam (go below water level) and fill and compact with clay, or to cut thru the dam, drain the pond, wait a year or so, and then re-dig (a few areas i'd like to make depper and level out one side of the pond) and use the new dirt (from digging the pond deeper) to fix the grade of the dam. Dont have any pics of the problems right now but if someone thinks they can help if I upload pics I will. Also, I am in southern illinois so if any members out there are in my area, i could host you for a visit to look at the problem first-hand. Thanks in advance for any help.

Hey All:

Was really hoping I could get some good advice on my post from the 10th of August. I'd really like to hear some experts input into my problem. Thanks.

Hey all,

brand new member and really excited about finding this site. I am really looking forward to some good advice on my pond. I have about a two acre pond with a dam on one side that i have been told is too steep. The dam also has leaks caused by tree roots and musk rats. I have gotten rid of both. Problem is I am not sure what is the next best step to fix the dam. I have tried bentonite in those holes I see, with limited success. I have been told to: cut a strip down the center length of the dam (go below water level) and fill and compact with clay, or to cut thru the dam, drain the pond, wait a year or so, and then re-dig (a few areas i'd like to make deeper and level out one side of the pond anyways) and use the new dirt (from digging the pond deeper) to fix the grade of the dam. Dont have any pics of the problems right now but if someone thinks they can help if I upload pics I will. Also, I am in southern illinois so if any members out there are in my area, i could host you for a visit to look at the problem first-hand. Thanks in advance for any help.

Hi Nightrider
all ponds leak, most dams are steep, alot of dams have trees and muskrats are common, digging a trench down the middle of a dam sounds complicated, you dont ask a question, you dont state if your pond is low (and alot of ponds are low this august), pictures help, goals and budgets are part of the feedback, you are new and your history with the pond is unknown, and you dont state who is telling you (ie. dirt contractor or nosy neighbor).

personally i am a benign neglect landlord and rooting around in the bottom and in the dam sounds like something that can wait.

cliffbrook, thanks for the comments. I will provide more details and will upload photos later today. I have owned the pond for about 15 years and have done no work/fixes to it other than to have the trees on the back of the dam which roots were pushing thru the dam, removed about 4 years ago. The pond is about 14 feet deep at its deepest (closest to the dam) but has lost at least 7 feet of water, much more than the normal evaporation i see each summer. Goal is to return the pond to its full measure by fixing the leaks. No issue with budget to fix the problems. Dirt contractors (2) gave me the advice on what to do next so since I perceive them to have a vested interest in the advice they gave me - i turned to other owners for a less biased response. Thanks.

Just curious, how many trees did you remove and how big were they? 4 years seems about right for the roots to rot away and create voids.

Also, where in relation to those trees was your water level when you noticed this?

Trees were all along the entire backside of the dam. Very mature trees. Water level returned to full after I filled the leaks cretaed by the tree roots and was good for several years. Last year I ingerited 6-10 muskrats that took up residence in the dam. I've gotten rid of them and filled all voids I could find with bentonite but water level continues to drop

What is the slope of the dam?

There are quite a few members from that area on here that are active.

seems to be very little slope as the back of the dam falls off into a large ravine. Surprised to hear quite a few members on here from my area -- as i have not heard from any of them to date.

any suggestions on the issues i mention?

I would do as you were thinking and dig a trench to drain the pond. Make it real easy to get rid of the silt and muck from the bottom and way cheaper than pumping. A pan scraper is the most cost effective way of moving a lot of dirt. And like you were thinking, line the water side of the dam with clay to plug up your leaks.

OK thanks i appreciate the advice. Would i need to wait a year or so to scrape away the silt as well as dig out those areas? seems like what i've read on the subject it takes at least that long for it to dry up enough to get heavy equipment into the pond.

The best fix if you want to get rid of the fish, start over and clean out the pond bottom is to drain the pond, dig a trench thru the dam and move all the muck to the back side of the dam. If you have good clay soil available on site, the contractor should dig a core trench thru the length of the dam, tying it into good soil on each side of the dam. That will fix the problems caused by any rotting tree roots and the muskrats, plus give the pond a fresh start.

Ideally you don't want any trees growing on the dam that are over 4" dia. Muskrats should be dealt with when they first appear.

If you just dig a trench thru the dam with water in the pond, the rushing water will erode a big hole in the dam, and flood down the ravine with no control. Pumping it dry gives you some measure of control on how fast the water leaves the pond. (If the ravine is deeper than the pond bottom, you can set up a siphon and not have to run a gas powered trash pump.

Great, thanks Esshup. The ravine is lower than the pond so i will try the siphon method you mention. I have plenty of land and clay on site and moving any muck to the backside of the dam into the ravine should work as well. I understand the core trench and agree. Any idea how long it will take for the pond to dry out enough to get equipment in there? Thanks alot for your reply

Time to dry? Too many variables to give a good answer.

With a trackhoe that has a long enough reach, work could be started same day. Muck can take from a few weeks to two years to dry out......