Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Replacing my culvert

Background....I have a 6-7 acre pond, 25+ feet deep at the levee. 8 years old.

I used an 18" culvert (which was what NRCS said was the recommended sizing for my watershed) upon construction and have regretted it ever since. Since construction we've had no less than 5 '100 year' rain events, and I've almost had water running over the top of the levee 3 times. I have a very large 'emergency' overflow that pretty much gets used once or twice a year now.

To make it worse, last year I had a big rock wash off my levee and into the culvert, essentially blocking it 80% or so, about 8 feet down. Nothing I've done so far has been able to get it out.

That's where I stood as of this weekend. I burned off the back side of the levee as I do every other year, then went in and cut/sprayed some of the saplings and brush that grew in - in the middle of that effort I found what is essentially a 50-75 gallon sinkhole about halfway down the levee - right in line with the culvert. I had the guy that built the pond for me come look, and he agrees something's going on there. He's going to come out and dig up that spot and see what he can find.

So with all this, here's my plan as of right now. I'm going to have him remove the 18" culvert and put in a new 24". I figure between the increase in rain events, the rock and now what appears to be some sort of leak, I'm going to take that as an omen.

He's telling me he can take it out and replace it without having to lower the pond level. I had assumed that wasn't the case.

Thoughts?