I Was wondering if it is possible that any of my fish could make it out of my overflow pipe. The pipe is about 8' down from the surface of the pond (in the deep end) and it is a 6" pipe with one of those yellow cage type ends on it. The pipe leads into an Agri-drain box that has removable plate sections to allow adjustment of the water level. So is it possible that a fish would swim through the yellow cage opening and into the 6" pipe during a storm where water was flowing over the agri-drain plates? I have smaller YP, BG, HSB, GC, FHM, GS. Not sure that this is even happening but just wondering if anyone else has experienced this or has a similar set up?

I have the AgriDrain inlet boxes on both my existing ponds and fish can definitely be lost through them during high water. I rescued hundreds of small YP on the outlet end of one of the pipes (12").

As far as I can come up with there's no way a standard 'surface' style overflow can be setup to prevent this totally...you can diminish the size of fish lost through grates/etc but then you're in danger of the drain getting clogged with debris easier which can result in some fairly significant/catastrophic issues - ask me how I know -

I think the best design is one that pulls from the bottom of the BOW - down below where most of your fish are going to be. It's taking out water you don't want anyway and your fish loss should be practically nonexistent.

Of course this type of drain setup has to be done BEFORE the pond construction is completed. Unfortunately.

I do not see why a bottom draw could not be installed after a pond is full. At least modest size ponds.

The pond would likely need to be drawn down a few feet and a little under water work might need to de done (securing lower intake point), but it looks like it could be done.

I have mildly contemplated it on one of my own ponds.

A bottom draw non siphon would be simplest to add to an existing overflow pipe but even a complete new, seperate, siphon system could be done. I'm no expert, but I do not see why it couldn't be done with a backhoe, proper compaction methods around the pipe, some elbow grease, and the willingness to get wet.

I do have the grate type or slotted plate sections that Agri-drain makes and have tried them with minimal clogging. I have been using them in the summer when we don't have as much rain, but in the spring I have used the standard style plates to allow the water to spill over and evacuate into the drain faster.

Has anyone ever designed a larger screen structure to put around the yellow cage at the end of the drain? If so it would be interesting to see some pictures or to know if that would even work. To me it seems like if you could build an enclosure using finer screening and place it around the drain it would reduce the number of fish that could enter the drain. I realize that the potential for clogging would exist but I think if a finer screen covered a much larger area, it would not be as likely to clog?

Yes fish can go through. I have a 10" pipe in my Agri-drain box and have seen lots of fish go through it with the standard inlet trash guard. Screening off the inlet is risky because it can become plugged. Taking water from the bottom is a good idea. All of these things have been stated here already and I just want to "plus 1" these statements because they are spot on.

Let me add two things. First taking water from the bottom may cause problems if there is a lot of sediment. Try to stay a foot or so off the bottom so you are not sucking in sediment. Secondly if you try to screen off your inlet pipe make a large box around your inlet. The more surface the box has the less chance of plugging up.

Lastly Agri-drain does make a fish screen that fits in the box but I have not used one yet. My ponds are weedy and I think it would just plug up.