On Sunday, July 19th there will be a masters swim meet at the Hains Point pool. They have various events and you must be a member of USMS to enter. Entries due by July 10th.
Here is also a list of open water events mostly in NJ & NY. http://www.usms.org/comp/calendar.php#COLONIES
I'm thinking of heading up to one in Barnegat Light, NJ (7/25)the evening prior to the NJ Triathlon. http://www.lmsports.com/