I've never had an issue of any kind with turtles of any kind. Sliders and snapping turtles come and go in my West Virginia ponds.
I just feel bad when I hook a tourist snapping turtle. If they have been deeply hooked, and I feel they might not survive, I will "dispatch" them and turn them into several delicious meals. I just really don't like doing it because I feel they do a lot of good work wherever they are visiting.
I've been around turtles of all kinds during my 68 years. I've never known of a "real" story of anyone being attacked by a snapper. The very few snapper incidents I'm aware of have been the result of stupidity (hey! Hold my beer!).
I also do not feel that any types of turtles, in reasonable populations (which, it seems like you probably have) significantly affect the food chain from plankton and snails to eggs, frys, fingerlings, etc.
If you compare the number of turtles to bass, bluegill, and other predators in a pond environment, they make up an extremely small proportion of the conuming biomass food chain.
