Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Pond Renovation Advice

Greetings,

I would like to hear your thoughts and advice on an issue I am having with my year old .5 acre fish pond.

The pond was built during a dry spell in our area, pond is roughly 14ft to the overflow pipe. The slope is steep, about 1.5:1 on the dam sides and maybe 2:1 on water inlet side. The pond collects water from the surrounding hills. Pond was constructed around August/September, but we did not see much rain until February/March following year. Native clay/soil has been used

During the filling I have noticed signs of soil erosion to a point where I can see limestone in some areas, mostly at the inlet side, and some on the dam sides. After filling up maybe 1/2 way, it dropped to 1/4, filled up half way again and, by fall of last year, dropped down to appx. 5 feet. During a major dry spell (appx 60 days of no rain ) water level dropped two 3.5ft at the deepest due to evaporation. Pond started filling up again after hard rain beginning of February in 2025 and after two hard rainfalls if filled up to appx 1 ft below the overflow pipe. It is March 11, we haven't seen rain for 3.5 weeks and I am down to 9ft of water at the deepest and loosing appx 1"in per day, but the rate of loss is slowing down as water level drops.

My thoughts: The base and lower section of the pond is sufficient to hold 6ft of water at the deepest but dams are the issue, where the pond is super leaky in the upper 1/2 or 2/3s of the pond due to either erosion, poor clay quality, or poor compaction. Looks ugly, big dirt hole with 1/3 of water

I understand that best solution would be to drain and rebuild the pond, bring in better clay, fix the inlet and apply erosion control measures but... I already have fish in the pond that I put in last year in the spring that I would hate to lose... I would like a chance to repair before rebuilding.

A thought that I have is to keep the base as clay, as it seems to hold water well, and wait until we hit the dry spell, water evaporates to the lowest and install RPE liner from the water edge to top of the pond. Basically have a hybrid system. Does this seem feasible? Or an idea that I should pursue? To procure 12ftX500ft liner and install is a lot cheaper than to line the entire pond. If I repair the walls with clay, I'm afraid it will not guarantee water retention. I would appreciate any comments or advice on this. Thanks!

I'm in the same situation with a 1-acre pond. The main difference is that I have a lot of sandstone and sandy loam soil. IMHO, the only way to seal is to use a significant clay liner (2ft thick or more) that covers the rock over and above the water line or, as you mentioned, a synthetic EPDM liner. I've spent > $100k on rebuilding dam 3 times, special polymer coagulants, and attempting to stay head of leakage by pumping in more water than I lose. None of it worked, and was an incredible waste of time, energy and money.

I will be using an EPDM liner when my budget allows. When installed properly, it's the only 99% leak-free water retention system. That means a liner covering the entire pond and tucked in 2-4ft past the top of the pond edge, well above the water line.

It’s always frustrating when it doesn’t work out first time and having to rebuild multiple times. Turns pretty expensive!

My question here is, if I only line just the dam with liner, and leave clay base as is,will the water find its way through? Will it work or another wasted effort? I learned quite a bit from reading these forums and understand my mistakes, too steep slope, soil/clay soil quality, etc… hoping to salvage what I have without doing a major rebuild.

Sorry nobody replied in so long, but yes, water will find a way through. There is no way I know of to stitch clay to a liner and hope water doesn’t leak at the junction of the two. It will. Rubber liners are all or nothing.

You do need to install them properly, and I don’t think a steep side will work well, so you may need reshaping so that the liner can be buried without materials sliding off of it. In smaller ponds you can staircase the slopes, and pin the liner with a layer of felt to prevent puncturing, and large rocks on the felt. A larger pond would be a big project to do this. The staircase will require a bit more liner, but has a lot of benefit to it for getting in and out as well as preventing materials from sliding. Also a place where plants in containers can be placed like lilies.

First I would try to drain it down in your dry season and leave enough water for the fish, and address the areas where you have erosion issues. Bring in some good clay, stir in some soilfloc, and compact it down in the suspect areas. Then place erosion control netting on top. Seed it with rye grass or similar to help hold it together. Pray for appropriately timed rain for a refill.

Thank you for the response, the reason I was asking here first is that I don't want to spend extra money on something that will not work. I was thinking to place liner (overlap) over the area that is currently holding. But regarding steep slopes it makes sense, even with clay it's an issue.

My best bet is to just let the water drain as much as it can during dry spell and just rework the pond walls with more clay. And hope for timely rain...

Due to recent heavy rainfalls, I had some additional erosion at the top, but it helped raise my pond holding level couple feet. I guess the eroded clay and sediment sealed cracks that I had in the lower levels. So I am a little over half full on average (7-8ft of water)