Something I have always neglected to look into before it's too late into the damage season, but does anyone have any good solutions to avoiding catching snapping turtles in their beaver lines in the summer?

Hancocks and snares and if you do catch one in a 330 do the right thing and eat him and you will feel a little bit better about the non target not as good as a beaver but a little bit better.

Don't set traps is the only sure fire way I've found. Caught them in everything but footholds and I'm sure I'll find one in a foothold eventually.
eventually. Of course if you think of the types of sets where a foothold is used will give you a start.
The sets where footholds aren't possible like channels, dive sets, den holes are all notorious snapper sets.

I just pretend that I'm trying to catch snappers and hope that one of those nasty old beavers doesn't find my 330. I call it "reverse thinking". Does it work? Of course not; but it does screw up your mind!

You trap for beaver in the summer?

It can be done, haha! This was from a muskrat job I did last summer on two VERY small ponds for a retirement community. I pulled on the chain and thought I was going to be pulling out a rat but it wouldn't budge. Therefore I grabbed the trowel and started poking around. After a few snaps on the trowel, I knew what I was dealing with. I learned two lesson from this job, always pack a shovel and don't under estimate the catch potential. I trapped 10 rats and of course 1 large snapper. Oh, and another lesson, the potential for extra pay. I almost doubled my take home pay by filling every hole those rats made.

Got to love snappers and counting fingers after you release one. Hatchets are useful for more than peeling sticks.

Dave, summer is usually the only time when we get the beaver calls.

Original post seemed to refer to fur trapping ("beaver lines") in the summer.

Get to deal with them even in the winter down here. 330 didn't kill it so it was carefully released with my setters. Summertime all I use is snares and footholds set deep.