The county owns it now and will take all the buildings down sometime soon. They’ll likely tear out the old parking surface too and replace it when they modernize the landing. I’m assuming here, but I think parking there may be a no-no until the finished park/landing is formally opened to the public. One can access the lake by parking in the county lot at the end of the road and walking out from there since that area has been open for public use for years.
Call the non-emergency sheriff’s number and ask if there is any rule about access there at the time.