Today on the way to lunch I looked in an urban water way and was delighted to see a japanese trap door snail!
Now on an ecological basis this is a very bad thing but now that I have a place I can harvest golfball and larger snails from I'm very happy to help reduce the population. The population does not seem to be taking over by any means, they have a very specific habitat and are only in those area.
I bought a bunch last year (they've doubled in price since then) but the coons ate them all.
In about an hour of active looking I found about 28 of them with the largest being a good 3 inches from point to point.
They are now in quarantine and are hopefully the start of a large colony as they are so expensive to buy from the wholesaler or to import.
I also collected some hornwort, elodia and anacharis and will be putting it through the same PP baths as the snails.