Pond Boss Forums Thread Like Summary - Newly Stocked Pond with Major Failure

Hello, I first discovered this site a few weeks ago and am amazed by the breadth of knowledge on here! Many of the threads have been incredibly helpful with information. I have had an issue come up this weekend and I decided to turn here for some information and advice.

I built a new 1 acre pond in 2021. Roughly 15-20 feet deep in the deepest location and generally probably around 10-15 feet in most places. It was constructed with sloping walls on most of the sides with a more gentle transition on 2 of the banks. This pond is primarily designed to grow very large bass.

I stocked the pond with 4-6in bluegill, catfish, lots of flathead minnows and a few sterilized grass carp for vegetation control in the fall of 2021. The plan is to introduce 8 - 12 inch bass this spring, after the bluegill have a chance to spawn.

Upon stocking the pond with the current fish, my pond stocking guy told me that we overstocked the pond and I would need to fish it aggressively after the first couple of years to cut down on the bluegill count. Originally the plan was to build a 2 acre pond as opposed to a one acre, however we ended up not being able to do that. However, due to a miscommunication, it was still stocked as a 2 acre pond instead of a 1 acre. No big deal, I was happy to fry up lots of bluegill in a few years.

Fast forward to this weekend. I went out to check the pond water temperature to see if it was warm enough to begin my supplemental feeding program and was devastated to see that one of the walls of the pond (essentially a dam wall) suffered a catastrophic failure. As I mentioned, the walls are sloping and not a deep vertical dive. I lost probably a 30 -35 foot section of the wall that extended probably 10 -15 feet deep (sloping). The overall pond water levels were down probably 5+ feet on average over the 1 acre. Suffice it to say, MASSIVE amount of water escaped the pond. To make matters worse, it was not a slow leak. I went to the pond 2 days before the check it and there were no issues. The water rushed out fast enough to take a tire off of the tire wall I had built for the minnows and leave a large trail of dirt and silt over a very large area.

Which brings me to my issue. I have gone to the pond the last couple of days and verified I still have a good bit of fish in the pond. This can be confirmed visually as well as I have seen quite a few bluegill and a couple of catfish come up to eat food as I utilized the feeder the last couple of days. What I have no idea of however, is how many fish I lost.

Technically, if I lost 50% of the fish, its not the end of the world, its just properly stocked. However, what if I lost 90% of the fish? What is all the bluegill stayed but I lost all the minnows and most of the catfish? My concern is I don't want to add another 50% of optimal stocking levels if I only lost 10% of fish, as I will be greatly overstocked now. However, I also don't want to understock my bluegills and not have enough forage fish for the bass once I put them into the pond. I cant think of any good way to determine how much fish I lost vs what is remaining in the pond. Same with the species, maybe I lost all of the Carp and now wont have good vegetation control. Maybe there are only a couple of catfish remaining out of what was stocked previously.

My dirt guy is going to reinforce all of the walls this week and also line all of the sides with clay to prevent this from happening again.

So I turned to the Pond Boss Forum to ask for some advice on the situation. What are your thoughts?


I included a picture of the failure below for context.

Attached Images

If that berm is part of the dam, there are a number of things wrong. Snipe hit them for you.
A properly constructed dam, even one for a one-acre pond, needs to be properly built. Compaction is a "must". If that blown-out section wasn't properly compacted in lifts/layers, I would expect the rest of it is the same. Fix the break and you move the weak link. It becomes strong, but if the rest of the dam (if that's what we see in the image) is the same, it runs the same risk. Having an emergency spillway is a must and you can see why.
Post a picture of the whole dam and entire pond and let's give it a look.

SSJ,

He won't toot his own horn, but I will!

Snipe is a pond professional that does consulting and raises fish for sale.

If you can get his eyeballs on your problems, then I would say that is definitely your best option for determining the cause of your bank failure.

If you click the blue "Snipe" in his post, you can send him a private message out of the view of the public forum.

Cody Edit - Snipe not only raises fish for sale, he grows high quality fish with high quality TROPHY genetic potentials with the extensive background knowledge of how to keep those fish growing to trophy sizes.

Just wanted to say I agree with what others are saying here. On this site the members feel each others pain and want to share in your success. They are speaking from the school of hard knocks. We have all had failures in building our dream ponds, knowledge is key to being successful. Don't give up, you will get there.

SSJ,

It makes my stomach a little upset looking at your beautiful pond getting ruined.

It is difficult to evaluate something over the internet, but yes - it looks like your contractor was not a pond builder. He did a beautiful job shaping the pond, but apparently did not understand the correct engineering.

Look at the next to last picture you posted. Do you see all of the plant roots still in their original position? That bank has NOT been cut and then compacted in lifts! It appears that he mostly just dug and shaped a "hole" on your property and called it a pond.

Lots of questions need to be answered before the people on Pond Boss can give you some good advice.

1.) Is the bank of your pond actually adjacent to the river? When the river comes up during a flood stage, will water be rushing past your bank? If so, that will always be exposed to significant erosive forces. You would need to take measures to protect your bank, but there are lots of rules about altering the banks of rivers and streams in Kansas.

2.) You talk about filling your pond with well water. Does any significant surface water run into your pond from the slope of the land after a rain event? If not, you do not need an outlet structure or spillway - as long as you don't leave your well on and flood your pond over the top of a bank.

If you do get surface (rain) water into your pond, then yes, you must have an outlet system and perhaps an emergency spillway. One of the most important factors in the design of the system will be the size of the area (acres) that drains into your pond.

3.) Even a perfectly constructed dam or pond levee is likely to be breached when water starts running over the top. The water usually creates a small crevice and that channels more of the flow into that spot, which works to erode a continuously larger channel, until the water cuts right through the dam or bank.

Looking at your first picture, I think most of us thought that is what happened to your pond. However, reading your additional postings, it appears that may NOT have been the case? Did water go over the top of your bank and cause the damage, or did the bank collapse with not a chance that the pond level was higher than the bank?

If the latter, then I think your bank collapsed just due to the poor construction of the bank. I suspect that as your pond filled, your banks slowly became water saturated. Did you walk around the perimeter of your pond after it was mostly full? Did you observe the outside slopes of your banks being soggy or even weeping some water?

There is a good chance that water slowly worked through that un-compacted bank where you see all of the plant roots. When the water reached the outside of the bank, it started washing out just a few grains of dirt. However, as those grains were washed out of the path of the slowly moving water, the path very slowly grew a bit wider each day. Eventually, there was a rapid flow of water and "whoosh" there went your bank.

Please examine your pond construction closely while thinking about some of the things people have written in your replies. Hopefully, you can then determine the likely cause of the bank failure. Take more pictures and write up your thoughts and observations. You must accurately diagnose the problem before you can determine the best solution.

Good luck on your pond repair!

I don't see a proper spillway. Looks water went over the top of the bank and washed away the bank.

That's what I'm seeing in the photos, the waterline is right at the top of the dam and obviously went over, no dam has ever been built well enough to withstand that, it usually drains the whole pond, cuts its way down as it goes.