The park reports on their Facebook Page that their beach closed on July 7 due to a blue-green algae bloom. This was a problem last year as well. Let's hope it is not a chronic issue this year!
Update: to check on the latest reported status of blooms in Cayuga Lake, check out this cayugalake.org link. HT to Shane Eversfield for sharing via the Ithaca Triathlon Club listserv.