Getting the water to drain

So I got this job for a big beaver issue at a lake that is 200-300 acres. Water is up at least 18"

The beaver piled seaweed and logs and now the leaves are falling over a grate that sits over the culvert (horizontal/flat grate). While trying to clear it off all the garbage just get sucked right back on to it. The suction is unbelievable

So I came up with an idea on how to hold back some water while I cleaned off a part of the grate

Cut the bottom off of a sump pit, flip it over and...
The water got sucked right out if it. So I cleaned out the leaves. I was going to set two 8" vertical pipes on it after clearing and then remove the sump pit

But there was no " suction " to hold the pipes.

So I lifted one side of sump pit about an inch and the water flowed hard in to it but dropped real fast through grate. The suction still held the sump pit. I then but the two pipes back in just to keep any leaves from getting in to certsin spots.....
Not sure if it will keep running and not clog. But I'll see tomorrow

Any suggestions welcome .

The beavers may plug it back up.

That's why I'm trapping them too


But I have to get this water down too, they are very widespread on the lake. But fortunately for me, they dropped a poplar last night on the two track I drive in on, so I set some traps around it today. Almost like they were trying to block me or challenge me lol

No beaver activity by it today and it's still draining

^ that is a good sign. I went and checked on a spot I was trapping beaver for a guy to see if they had plugged up a crossing again. This guy took a backhoe and opened it up and it is still wide open. I must have caught most of them which was good to see. Idle water is an invite for a new home for beaver.