Pond Boss Forums GENERAL QUESTIONS Property Projects & Construction Keeping fish in the pond during heavy rain

With a low shot at a tropical system this weekend, I thought maybe it is time I asked this question:

How do I limit the amount of fish that exit the pond through my spillway without it clogging up with fall leaves?

My first thought would be to put up a screen of some sort, so only the smallest fish would fit, but that is a recipe for clogging. Another thought is to build up a wide, flat spillway that water would cascade over. I would make it wide enough to handle a decent volume of water without getting too "deep" in any one spot. Perhaps made from treated lumber or poured concrete.

I could also put fish-heads on tiny steaks at the pond end as a warning like in medieval times, but that seems a little extreme. ;-)

Any ideas?

In order of success I'd do the following:
1) Fish heads on stakes
2) Make the spillway as wide as possible to limit the water depth that exits the pond.

I use the wide spillway idea, then tell myself nothing goes out I have went to look and try to find any fish that have gone down the road and never found any.

Living along the gulf coast we get alot of tropical weather. I have designed everything I built for my family from the mid 90's with a way to drain the water down before a storm arrives. The method I like the best is a 4" slide gate valve at the bottom of the pond connected into the stand pipe. We build in a grated box with 1" holes around the valve to prevent losing anything of size. Also we use gasketed piping for the top couple feet of the stand pipe that can be removed to drop the water level if need be. I can still remember many years ago walking around in a storm picking up Catfish in a couple of inches of water out of the pasture from the spillway.

Gate valves in the water (water side of the dam) tend to stick over time. We have them and I have engineered around them. Way to much trouble when there are easier methods to use. Last lake I made them take the gate valves back during construction. Instead used a combo of siphon (self starting) and angled 6 in pipe into the main pipe and a top overflow pipe. When the water rises above full pool the 6 inch pipe starts to remove water from 5 ft deep. When the water rises 6 inches above the angle pipe the 6 inch siphon starts . 6 inches more and water goes over the top of the main 30 inch pipe. If the water goes up another foot the emergency spillway starts. Even in catastrophic storms (hurricanes and 20 inch rains) the water has not gone over the emergency spillway on this lake. Not so on the other lakes.

Same rain event 3 lakes

Spillway and siphon wash out







Gate valve and 48 inch pipe under 4 ft of water ES in use



normal full pool




Lake with no valve 3 pipe system - water only up 3 feet on to dock and 1 foot below the ES.

I don't have a heck of a lot of options as my pond *only* has a spillway. Last winter left me sweating when we had a very heavy downpour with nothing to prevent erosion. Grass does not grow well in frozen ground! I wound up with some pretty deep channels I had to fill with stone and clay, and the pond was only 3 months old.

Then I found this site and realized that it would have been nice to have a drain pipe installed when the pond was built. I may consider installing an automatic siphon to take the load off the spillway, I just would like to keep it concealed for aesthetics.

I now have some reasonable grass growing, but not mature plants yet. This summer was so dry it kept killing my seedlings. It is better than nothing, and in another week or two will probably stop all but the worst rains from doing damage.

When I do get runoff, I have about 8-10 acre hillside running into a 0.6 acre pond. A lot of water in a hurry. Last winter it was approx 1" of runoff rain = 18" of water in the pond. Seems like forever since that has happened!

I have my fingers crossed we will get ~2" which would top things off without problems. Our 0.56" today resulted in no runoff, but we gained back what we lost in the previous 5 days.

You might try construction silt fences. They're designed to control silt, but let water through. I have used these successfully in erosion areas.

They're cheap, fast to set up, and if they don't work, you can take them down quickly. I always keep a few rolls handy, and just stick them up with T posts.

If it was me, and that spillway gets used more than once per year, I would get a siphon/overflow pipe in there as soon as possible. You wouldn't have to drain the pond to do it. Seems like you will be constantly doing maintainance on the spillway if it is used frequently. Do you not want the whole spillway out of stone/concrete? That would be less long-term trouble for you.

Just my guess on this, see what others think......

So far I have been lining the spillway with loads of collected 3-4" stones, and plenty embedded in the clay, then grassing in-between all of this stuff.

I am worried about lining it with cement without excavating down below the frost line as frost would push the whole works up, then water would simply go under it. I may do this, but not until my bank account and wife are for it. I would have to excavate a ditch 3' down across the spillway, and pretty much build up a poured concrete foundation. This solution would likely last darned near forever though.

I drew up some plans, but there is an amazing volume of concrete in my solution making for a costly problem, compounded by making the spillway as wide as possible. I would need concrete delivery to deal with the volume as I could not mix enough by hand without it stratifying allowing water to seep in over time. I am cautious of cementing blocks rather than a solid pour as again frost and ice could simply blow them apart.

As the forecast draws closer, it seems more likely we are going to get nailed. Still not certain yet, but more and more models are starting to shove the beast inland over us. One of the solutions is predicting an absolute mountain of heavy, wet snow!!! I always wondered what a tropical storm plus winter storm may create, but not at our house. Especially when I have to leave my wife and kid at home while I am away in Tallasee, AL during this event. *shudder*.

Might want to look into a generator if you don't have one....

Heavy wet snow + trees with leaves = lots of broken branches and trees.

Liquid squid if you think you may have an erosion issue at the spillway you can go to a lowes or home depot and get the heavy mil plastic and put it from the pond over the main spill way. You need to put one end down below the water level in the pond, I suggest to use rocks or blocks in milk crates to hold it there. The milk creates will also serve at a barrier to keep fish in your pond. I have used just milk crates as a way to keep fish in while allowing water to pass.


Ewest being around saltwater alot of my life made me understand if it will rust it will have problems and the need for redundancy. That is why I went with the composite / stainless valve that was basically corrosion free (got them thru Wallace Pump and Supply out of South Alabama many years ago). I just recently (a few month back) inspected one in the 3 acre pond that was installed in 1998 and it has no rust (even the stainless bolts where high enough grade they are still pretty). I have not had a single sticking problem with them. Like you say you have had with yours, I also know people that did not go the corrosion resistant route that have had problems with theres. Also not knowing when I originally installed them if I would have one stick I built in flange bolted ball valves at the other end of the pipe. Anything I build that I do not care to have to do over has a backup fail safe redundancy plan. That leads to why I over built my personell ponds for tropical conditions (many ponds have been breached in my area from tropical weather). Every pond I own has 3 permanent methods (siphon system, stand pipe / pipes (as many as 4) and valves) of water release other than the spillway. I also have irrigation pump mounted on a pull behind trailer that is pto driven that can be located where I need it. This pump moves enough water to power a irrigation real at distances of a 1/4 mile away. When you can get 20" of rain in tropical system you have to ready to move the water.

I like the idea of weighted down plastic for a quick way to possibly avoid spillway damage. You just better not have/leave/forget it there to long, or all the grass you've been trying to grow will be killed. Its easy to forget small stuff like that.

This is a FANTASTIC idea. I actually have a large chunk of ploy pond-liner and heavy-duty pond-liner underlayment (1/4" landscape fabric) that I was going to enlarge a pond garden with before I decided to go with a real pond. I have been wondering what to use those materials for as my pond garden idea has more or less been abandoned. Enough work already on the main pond.

The fabric will do a great job of keeping the water flow rate at the surface low due to friction, the rubber liner I can use to extend away from the pond further. If only I could lift that dang roll of rubber! It is a 20x20 liner of the thickest stuff I could find, and probably weighs 200-250 pounds. The fabric is easy.

Sucks even more that I will likely be out of town. I love to watch a good weather show!