A crew from Miller’s Launch came up the North River early Thursday with mooring balls to be installed for seasonal use at the Parks Department’s Dyckman Street Marina. With the 79th Street Boat Basin out of service indefinitely, Dyckman Street Marina is the only recreational access point on the New York City side of the river north of 58th Street and the only spot with moorings for visiting boats. This too could disappear for a few years if a Parks Department plan to rebuild the marina next year goes into effect.