I normally conceder beavers a bad thing for a pond, but after some recent flooding in the creek near my 9 acre pond displaced a couple of beavers into it, I'm rethinking it. After the recent hurricane in SC dropped an enormous amount of rain on the state, my pond was running over on the backside off a natural wide low spot that dumped into the creek. Something it rarely does because it is spring feed. Well the two displaced beavers decided all that leaking water was a terrible thing and started raising the bank height along the back of the pond, increasing the pond height 1'-2' currently. Now the rest of the pond has quite high banks, so it's not a problem right now and I really conceder this a win for me. I have thought about taking the backhoe at some point and reinforcing there work while installing a drain pipe to handle future run over and try to keep the current level.
Now,I'm not 100% sure their still in the pond as I have not seen them lately at dark, but at what point does this become counter productive to the pond? Or does it until it runs over? A few of the trees that used to be a along the shore edge are under water, but are plenty others behind them.

Is that 'natural wide low spot' where water would normally overflow if he beavers weren't there?

I have a spot like that on the Southwest side of my pond. When yer done with those beavers, please let me know and I'll send you money to buy them bus tickets up to my place!

Tim, the beavers around my area of Texas seem to consider a dam as a great place to tunnel into for a new den.

How did you train those suckers to do that?

Yes, that low spot were they dammed it up is the natural overflow for the pond. Although in the last couple of years I have only seen it overflow there twice maybe with the exception of the hurricane.
The last two beavers that came into the pond from the creek cut down one of my wife's favorite shade trees by the water, she had me trap them PDQ. She has been pretty laid back with these two.
The beavers said Texas is too far on a hot bus, how about a coach flight?

You'll want to watch out for tunnels. They can breach a levee lickety-split.

The other issue to consider is water rising to the point it can breach the dam. You don't want water flowing over the top of your dam...ever. That's the most common way a dam can fail, is overtopping.

Thanks Bob,
Dam breach has never really been a concern to me, my pond was a sand mine originally and really has no dam to speak of. All sides are up hill 5'-6' to level ground with the exception of the area that is the low bank area and is a natural spillway. There it gently slopes off two to three hundred feet dropping maybe 10'-15' in that span to a creek. The whole area has a good stand of small hardwood trees and seems solid, I don't see anything ever moving. And when it did spill over it would be 15' wide and 1"-2" deep. But I am not a pond engineer by any means.

Lusk's comments would pertain to a pond created by a dam, so you're Ok with your situation, mostly.