Last year I sent a letter to the festival organizer asking for dink access, or at least his support for it, and got a response that indicated he had no control over it, and I needed to take it up with the county executive.
(EDIT: Just found this on the festival website. Emphasis is mine...)
The Clearwater Festival at Croton Point Park is located half way between NYC and Poughkeepsie, less than an hour train ride from New York City’s Grand Central Terminal or less than an hour train ride from Poughkeepsie’s Metro North train station. By car, the drive is about an hour north from New York City or about an hour south from Poughkeepsie. Croton Point Park is located one mile from the Croton-Harmon train station. Due to Parks regulations, audience members are not allowed to arrive by boat at the festival.