I'd say that when the landscaper showed up to seed/sod the lawn, these logs were in the way, so he just shoved them into the pond out of his way. Pond probably isn't done yet anyway, needs critter guards on the pipes and should probably line the pond with erosion stone or seed it and cover with mulch blanket.
If the logs were full length and still had the stumps attached we would call them habitat logs. The rootwads provide habitat for everything from fish to birds to frogs. I won't let people put them in ponds though! These habitat logs are usually part of a riverbank stabilization or wetland creation project. Those logs look like trash dumped.
You need to find someone on grounds crew, maintenance or contractor's group; and ask if they care if you took those "dumped trash logs" for your woodpile. All you need to hear is 1 "sure" and you're in the clear!
And clear access to it. Problem is that the ramp is really steep and hard to tell if its dirt compact or cement there of some kind. Well a possible weekend job that's for sure but this is a new school and its gated off all around so we'll see. Nice logs though!