I bought a property with an existing 1-acre pond that was neglected for 20 years or more. I literally couldn't walk across the dam, because it was so overgrown and had a dozen or more trees growing on it, and it was seeping water all across the base of the dam. I hired a local excavator/lagoon/pond builder who removed all the trees, cut a gap in the damn wide enough to drive a bulldozer through to drain it and push out all the old muck, got the entire pond back down to hard pan clay, rebuilt the gap they cut to drain it, rebuilt the inside of the dam and cored it. He finished the 1st of November 2023. I live in Mid Missouri, USA where we have a lot of clay. I watched it closely as it filled over the course of 2024. It was late in the year, but I sowed winter wheat on the top and back of the dam and rye grass inside the pond, and it all actually came in nicely. We didn't get much snow/rain in the winter or spring but received record amounts of rain in May/June that filled the pond completely. So much so, the excavator had to come back out and lower the spillway and added dirt to the top of the dam. I watched it closely as it filled and observed no leaks on the back of the dam anymore...that is until it got to about 3-5 feet from the top of the dam. The dam leaks (or seeps) very slowly in two spots at the base of the dam in the location of where the dam was cut. The seep is enough to wet the surrounding area behind the dam, but not enough that I can actively see it flowing or cause a noticeable drop in the water level. I have not been able to get the excavator to come back out and take a look since he redid the spillway. My guess is that the dam cut didn't get properly compacted near the top of the dam where it is very steep. My solution so far has been to apply 700lbs of bentonite clay in granular form to the area of the dam where the cut was made in two different applications, the first 200 lbs of which was late July and the last 500 lbs yesterday.
Finally to my question, would it be normal for a pond to leak/seep where the dam was cut and will it stop eventually as it silts in? I don't plan to add anymore bentonite this year, but should I continue applying it if the dam is still leaking next year? The lagoon I had dug (by the same excavator) also had a small leak, but it did eventually stop leaking after about a year.
Thank you for any thoughts or advice.
Last edited by ChristopherD; 09/12/24 01:38 PM.
