Pond Boss Forums POND CONSTRUCTION Building a dam Culvert Outlet Below Water Level

If you plan on having CC in the pond, the culvert might make good spawning habitat for them if it's under water. I don't know how that fits into your fishery plans.

Even with the elevation drop from inlet to outlet, depending on where you are measuring the water (bottom or top of inlet pipe?) at spillway level you potentially could be also dumping water out of that pipe.

Also, depeinding on the water level in the pipe, any stagnant water creates a good breeding ground for mosquitos. I don't know if they'll fly 90 feet to the water, but they surely will fly 5 feet or so, possibly more to get to the stagnant water inside the pipe to lay their eggs.