Pond Boss Forums INTRO Questions & Observations Concerns about fish going over spillway?

With a lot of help from TJ and Seek Leek, and Mother Nature, I think I might see my pond flow over the spillway for the first time this weekend if we get all the rain they're calling for.
Do you guys worry about your fish going over the spillway? If so, what do you do to try and stop it?
Thanks!

In my area, most spillways are virgins. I think, in about 40 years, each pond has overflowed once.

Except for one rain event where one spillway was actually utilized, my ponds drain through 8" tiles whose inlets are blocked with netting and a grate to prevent any large fish from exiting. Before I put the grate on the second pond, I got to walk through the woods below the drain collecting YP and SMB, trying to get them back to the pond alive. No more.

I have a drop inlet box at the edge of the pond water for my overflow and every spring rain you can see tons of small minnows going over the box into the overflow pipe.

I do have cattle panel guard built around the basin to keep big trash from stopping it up, just the other day I added some really fine shaker screen to the cattle panels on both sides of the box from the shore line so that small fish that habitate in the weeds and brush along the shoreline, will have to swim out into the open water about ten ft and come in the end of the opening, which I am hoping will help immensely with the loss of minnows.

I will try to get some pictures of it next time I go to the farm.

Those little minnows seem to be enamored with the water flow dumping into the box, you will see tons of them trying to sit there and swim against the current at the edge of the box till they lose the battle and get swept into the drain.

Congrats on stopping your leaks!

How much water will be going over the spillway? Is it just an earthen emergency spillway?

You can always just put up some chain link fence and make it "progressive". By that I mean put 8" of fine mesh fencing at the bottom of the chain link so you don't lose any valuable fingerlings. If the spillway flow rise higher than 8", then the chain link will hopefully retain your larger fish. As the depth of the water flow increases, it will start exerting a LOT of force on your fence posts. They need to braced t-posts, or actual driven/cemented fence posts to survive.

The pressure on the fencing will be even worse if floating sticks and leaves can accumulate on the fencing.

If you are usually going to receive smaller flows over the spillway, you could still easily install a siphon system at your pond. (Especially if you have a low area behind your dam.)

You can put a screened inlet in the middle of the water column and set up an automatic siphon system to start moving water over the dam BEFORE it reaches the spillway elevation. That will save all of your fish, except for the heaviest rain events if sized properly for your watershed.

(PVC gets much more expensive and much more difficult to seal perfectly as you move to larger diameters. You cannot have any pinhole air leaks in a siphon system.)

Hope that gives you a few ideas, since you are the one with actual eyeballs on the project.

Now that you have reduced your worries about your pond running dry, lets not add the worries about losing your fish!

Thanks guys,! I need to add that I only have a earthen spillway, no drain.

I also have an "earthen" spillway that has is about 10ft wide and filled with rocks on geotextile, with a 4:1 slope heading into the spillway. With that setup I have lost many minnows and I imagine I lose some fry, but using a range of rock sizes and a few feet of shallow rocky area I have not lost any adult fish, which would be caught in downstream pools. I personally like this better than the fence since any leaves or sticks get washed over the rocks and don't fully plug the spillway, if it gets bad. I also control the inlet flow to the pond by diverting excess flow and have not seen more than a few inches of water in the spillway. Not 100% guaranteed but seems to work.

FishinRod, I haven't completely stopped my leek, but I've improved it a lot. I cut my losses per day by more than half, maybe down to a third of what they were. I might treat it again later.
I will only have water flowing over on the bigger rains. My water shed area isn't very big, so I wouldn't think I'd have a lot flowing over.

I have thought about some type of fence, and I've also thought doing something with rock to kind of make a filter.

Retired on 40, what all sizes of rock did you use? I don't think my spillway is as wide as yours, but it is pretty wide. I can drive my truck through it. My spillway area is the least steep area of my whole pond. I can't say for sure until I see water flow over and see for sure where the highest point is, but my slope heading in might be close to 15:1.

I went down about 9:30, and checked on it (in the dark) and it had come up 20 inches so far, and hard to say for sure but I don't think I had more than 12" or so to go, It was still raining and water flowing in hard from the sediment pond. I think most of the heavier rain is over, but it is still raining and supposed to rain most of the time till tomorrow evening. I will be surprised if it isn't flowing over by morning, there is a good chance it already is. Hopefully I don't lose any of my biggest bass.

Thanks again guys.

Still not full, but maybe only 2 or 3 inches to go. Some water still running in, just started raining again, and they show over an inch possible today,so I think it will still flow over today.

My pond did finally flow over the spillway for the first time today! Unfortunately, I had a busy day today and had to be somewhere else, so I only got to look at it for a few minutes. The way my spillway is designed, the flow was pretty gentle. It is pretty long, level and wide. When the water enters the spill way, it is only 2" or so and keeps getting shallower for about 15' or so before it starts flowing down hill, which has about the same slope. Hopefully it will still be flowing tomorrow, and I can check it out more.

Congrats on the full pond!

I agree with Retired, fences around a pond are generally pretty ugly, and rocks are usually better if they can also accomplish the task.

If your spillway is fairly wide, I think placing a small triangle (profile view) of cobble size rock would keep in a lot of fish except for your most extreme flow events.

I once watched hundreds of 3" shiners go over my spillway. Wish I would have had a net.

Accept it as a part of nature. Usually more issues with debris getting stuck in the netting or wire panels and reducing water flow when you need it most.

Thanks FishinRod! It has been a long time coming! They finished building it 8-25-2017. While I got lucky with the rains, I have no doubt that it still wouldn't be full without the help of TJ and Seek Leek!

The rain pretty much stopped Saturday evening, but still have a small trickle this morning. I did get to spend a little more time checking things out yesterday. It is probably mor like 4" deep where it enters the spillway. I didn't see any sings of minnows going up in the spillway.

I think your right. If I do anything, I will try rock first. From what I seen the last couple of days, I don't think I'll have a big problem.

Since I drive over the dam to the road I installed 2 24” drain pipes and a retention pond on the down side and it hold the escapees. Then either net them or minnow trap them back into the pond. It works for me….

We received six inches of rain Sunday afternoon into Monday morning so needless to say our drainage ditch was rushing into the pond. Our 3 acre body of water rose nearly a foot!

I walked the property yesterday and did not find any fish below the spillway! We've installed 2 fence posts with mesh wire across the spillway. Small fish could pass through, but I didn't find any. The mesh wire is collecting lots of TRASH for sure!

One thing I'll say that might benefit others is to ensure during pond construction your spillway is wide enough. Our construction certainly has some faults, but the spillway was done very well. It is wide with an ever so slightly downhill slope. The water is easing out instead of rushing out hopefully eliminating erosion issues.

I wish I had a good spot to put a little retention pond in. The way my land and road lays, it would be hard to do.

I envy you guys. My biggest pond has overflowed exactly once in 25 years.

Dave, it took me 7.5 years.lol

Bob, I’ve recently had some dang good rains. Now only 3 or so ft low. About as good as it gets.

My spillway runs 6 months out of a year, which is shallow and wide. I have irises and other plants growing in it which act as a blockade for larger fish. The iris make a foundation almost impossible to wash out. But not everyone can do this, especially if there is infrequent water in it for thick rooted plants.

So far I am unaware of any fish that have pale it over.

Well after my pond flowed over the spillway for the first time back at the first of the month, it dropped way more than I hoped it would. But last weekend we got enough rain that it was flowing over harder than the first. This time there was a lot of tiny BG going over the spillway. I would say the biggest ones were about 1 1/2". We manage to save a lot of them, but sure a lot washed down because I didn't get to check things out for several hours after the rain had stopped. They were washing out faster than we could pick them up, so my daughter kept picking them up while I got out my little tractor and gathered several buckets of rocks from 2"-10", but most were probably in the 3"-6" range, and dumped them in the spillway. After about 3 hours of doing it, I started running out of back and time, so I scraped up some of the larger gravel on the side of my road and dumped it on it as well. Got a little more fines in it than I thought, and blocked more flow than I wanted, but kind of liked it afterwards, when it brought my pond up a few more inches. I plan to add some more rock when I can, but stopped seeing fish getting pass after about an hour of working on it.

I still had a very small trickle flowing over the spillway today.

I would be more worried about it if it was late Fall instead of in the Spring. You will have a LOT of BG spawning soon and they will replenish the population shortly.

Personally I really don't worry about overflow causing a problem. If I was really worried about it, I'd call in a company to elextroshock the pond to do a population survey and then adjust the remaining fish population based on the electroshock survey results.

Our 50 acre lake runs through the spillway more than half the year, and that's with the 6" bottom drain wide open. Late summer it will drop done and even close the bottom drain for a couple of months. Part of it is spring fed and over 2000 acres of watershed. Normally a few inches going through, but a 6 or 7 inch rain will push it to 4 feet for hours. We definitely lose fish when that happens. We're probably going to try fencing the spillway to try and save larger fish, maybe the 2"x4" wire.