The U.S. Coast Guard and EPA have closed the Gowanus Canal to all recreational boating between Butler Street and 9th Street through November 30, 2021. From the Coast Guard’s updated Notice to Mariners:
The Gowanus Canal is closed to all recreational boating between 9th Street and Butler Street, including use of the 2nd Street public boat launch, at the direction of the U.S. Environmental Protection Agency (USEPA), the lead federal agency for the Gowanus Canal Superfund Site, due to the ongoing construction of the dredging and capping remedy of the canal until further notice unless specific advance written authorization is granted by USEPA. Contact: (212) 637-3639. For further information: https://gowanussuperfund.com/
You can see the complete Notice to Mariners here.