Pond Boss Forums INTRO Questions & Observations what constitutes full pool status?

In another thread (my sonar survey), esteemed Pond Bosser Esshup asked me if my pond was at full pool (different from fool pull, I think).

I replied like this:
Well, we aren't completely sure just what water level is full pool at our pond. With all the work we did on the drain box and installing the shutters, we have the water at the level that we think is normal. I could raise it at least another foot and I think it would still be safe for the dam. But, the reason we haven't raised it is because we want to leave a margin of safety in case of a massive rain event.

I suppose your question would raise another question for me - what exactly is full pool? How does one determine that?

If my water were to rise another 3 feet from what the level is currently, it would begin to pour in over the top of the drain box (a 6' x 9' concrete structure that is completely open at the top). I've only seen it that way once - and our spillway area was running water at about a 3 inch depth. We believe that the spillway area is really intended to run only for emergencies and not normal levels. This was a 100-year flood event and our drain box was pretty much at capacity. At this event, we observed that water was only about 2 feet from over-topping the dam.

So, currently, our water level is 5-6 feet below the top of the dam. That feels right but, someday I'll get Greg Grimes to come and look...when I'm not too broke to pay him.

Which got me to thinking...always dangerous! Anyway, if you get a pond well after it was built and you have no idea who built it then, how do you judge what is really "full pool"?

Al, my idea of full pool is where it almost runs over or through outlet pipe or spill way or?

In my case, I have a through the dam 12 inch pvc pipe. A foot above that is an emergency spillway over natural ground. If it reaches the bottom lip of the pipe, I am at full pool. However, I've only seen that once.

Thanks, Dave! Good answer if you're using a standpipe system, I think that's the right answer. Since mine is a box with shutters, I think my answer might be different.

More opinions? Expert answers? WAG?

In my mind (uh oh, this could be a mistake), full pool in any BOW is determined by the point at which it begins to exit, regardless of the method used to control the exiting water.

I agree.

hmmm...OK but, that still leaves me with the question of shutter-type systems like mine. I could completely close all my shutters and the water would (after a couple of weeks) rise 3 feet and then begin to exit. Or, I could remove all my shutters and the water would immediately exit and drop my pond by more than 3 feet.

I've got it about in the middle right now...am I 3 feet above full pool or 3 feet below?

When my pond's overflowing the surrounding levee's, I've been saying it's "above full pool". When it evaporates down to the original ground level, I say it's "down to full pool". Now I can't enjoy thinking I have extra water, thanks to you!

"Full Pool" is really just a feeling. If it feels good, call it "Full Pool."
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.I do agree with the spillway reference, or when water starts to, or is close to exiting.

For me, full pool is as high as you want the water to be in a semi-permanent timeframe. Many people have a thru the dam drain device which begins to, as Brettski describes, exit the pond at full pool. It doesnt bother that it rises above this for short periods of time, but not stay that high for longer periods. Example, above full pool, the water comes out of the basin in the shallow end, covers vegetation and small fish have a very shallow refuge. If it remains that wasy for too long, not good for the looks surrounding the pond, or for larger fish being able to forage.
All that being said, it sure is nice to start out the spring with the extra water. Especially, for me, this year.

DID I OVERTHINK THIS, OR WHAT?

My idea of full pool with a shutter system is when all the boards are in place and it's just starting to go over the topmost board.

"DID I OVERTHINK THIS, OR WHAT?"

Yes, you did. But then again, you wouldn't be here if you didn't!

OK, this is fun!

I think I'll leave what I've got for right now. It is GREAT that the drought here is over and I know that I could put in another board or 2 and it would fill up quickly to that level.

We're supposed to get a week's worth of rain starting in the next day or 2 but, I'm not going to try to catch it yet. However, sometime in June our traditionally dry, hot season will start so we may go ahead and try to capture a bit more since evaporation will soon begin to take it's toll on our water level for a few months.

Al it's funny how often a 100 year flood occurs here in Texas. I have lived in the Dallas area now for twenty years and we have already had two of them. The last one happened about four years ago when we got nine inches of rain in a very short period of time. My pond went two feet above full pool and two feet over the emergency spillway. After that I had Mike Otto construct for me another emergency spillway for the next 100 year flood. My only point is that I would make sure that if you continue to raise the water level you are feeling fairly secure that if a 100 year flood does happen your spillway can handle it and take the water away from the back side of the dam.

I think I'm probably being overcautious but, I'm fine with that.

3 extra feet of water doesn't do much for my fishery - now is also sorta in the middle of spawning for 2 or 3 of my species so, it might not be good to go messing with water levels right now.

However, given my topography of the whole area around the pond, adding 3 feet of water would add almost an acre of surface area to my pond. The thing is, it would mostly be unusable surface area because it would mostly just flood areas that have dense bushes and trees. Later in the year, it might actually help with the subsequent spawns and survival of some of my shiners, though. They would have more protected areas.

For me, I'd got with whatever extra surface area I could get, in a general sense. But I also agree with james and have to suggest that you must make sure your dam can handle the extra load, in normal and flood situations.

I should have said this in the very beginning but, my pond is really a kind of "impoundment" of a perpetual stream so, there is not really any time (except during the worst of the drought) that water doesn't run out of my pond. I'm guessing that is why they put in the shutter system.

Though, it could be said that my drain box is kinda like a gigantic standpipe if I block off the opening by putting up all the shutters and letting water pour in over the top. But, that would leave practically no safety margin other than the spillway and water would be within a couple of feet of overtopping my dam. I don't think I would ever do that.

The other 2 factors (which we control rather religiously) are: beavers constantly trying to build in front of the shutters; and all that floating timber - tons of it - that tries to float it's way into the box. We keep all of that stuff cleared out - at least once per week.

And that explains, in large part, why this question is so interesting to me. I have to protect my dam! If I were to lose the dam, I can neither afford to rebuild it nor could I ever get a permit for it.

There may be liability on your part also if the dam fails however extreme that might be.

You must like the current PB article about beavers and how to best control them.

Last time I saw my pond was after I raised my level 3 feet.....looked like a Muskrat had damaged the area near the spillway and I had lost 2 feet of thickness on top of the dam....I hope the pond is still there since we can't get there now and we have had several big rain events.

I hope that widening my spillway 8 extra feet was enough to alleviate the extra pressure when it flows....I only have the spillway for the excess to leave the pond.

Sunil has a good point but in that part, I'm lucky. I own all the low land for about 1/2 mile below my dam and it's all just wild. The nearest structure is more than a mile below my dam. So, in terms of liability, I have pretty low risk - practically none. The worst that would happen would be to give a good soaking to a hay field.

I still don't have my new issue of the magazine. I can hardly wait to get it!

My game warden friend that lives near my pond is supposed to come out and trap my beavers again pretty soon. I know I'll never be completely rid of beavers there. If he gets all the current residents, more will come to the area eventually. So far, they are only a very minor nuisance.

[quote=Rainman]I hope the pond is still there since we can't get there now and we have had several big rain events.
[quote]

Too busy running with fish or other reasons?

Rainman has had some legal issues with his neighbors, and has effectively lost the right-of-way access to his pond.

A real bogus situation no doubt.

I knew that a new jugde was going to take office and that he (Rainman) thought that it would help the case. Hopefully, all aveneues haven't been exhausetd. It's bogus all right.