Is it a common problem for beaver snares to become non-functional because of grass or other small debris flowing downstream and disabling the snare?

Never have any issues unless we get a BIG Rain.

Yes but it depends on the stream
When leaves are falling it can be bad

If I did, I wasn't going to catch anything that night anyways as the snare would be completely out of position.

Not if you set them on the land outside the water.

There is that lol. It is where I prefer my beaver snares but sometimes laws or circumstances force you into the water. Then again some of my dry beaver snares have been know to be under 10 feet of water during the right time of year...which is most of the Ohio beaver season.

Sometimes i go up stream about 7-10' from the snare and push a thumb wize stick into the stream bed leaving about 6" sticking up out of the water. Helps catch/divert some of the junk

Clever. Do you just keep the snare inside the "V" this creates in the water?

Here,springtime after ice out is the worst for fouling any kind of set in current.Lots of loose dead grass and sticks floating in the high water.Even totally submerged setsin current are prone to fouling in spring.In the fall its not a problem.

Red89, yes. I set the snare then place the stick. It doesnt keep all the debris out, but it helps a lot.

I kinda like that idea.

Take 4-5 sticks and make a diverting wall just upstream of your snare. Push into the bottom and angle with the current to divert garbage and ice chunks around set snare. I see no need to go 7-10 feet upstream, but whatever works.

I do the same thing with conis a pile of rocks a few feet in front of coni diverts most floating crap that clings to triggers