Question: Of which river is the body of water, that marks the change from Grand Street to Grand Avenue, a tributary ?
Context: The Grand Street Line is a public transit line in Brooklyn and Queens, New York City, United States, running mostly along the continuous Grand Street and Grand Avenue between Williamsburg, Brooklyn and Maspeth, Queens.  Originally a streetcar line, it is now the Q59 bus route, operated by the New York City Transit Authority between Williamsburg and Rego Park, Queens. Grand Street was a train station along the Evergreen Branch of the Long Island Rail Road.  The station was built on May 15, 1878 by the South Side Railroad of Long Island between Metropolitan Avenue and Grand Street (Brooklyn) at the East River Ferry.  From the Greenpoint Terminal it took 10 minutes to get here.  Grand Street was closed on September 28, 1885. Grand Avenue was a station on the demolished section of the BMT Myrtle Avenue Line.  The station was opened on April 27, 1889 at the intersection of Myrtle Avenue and Grand Avenue in Brooklyn next to the Myrtle Avenue station of the BMT Lexington Avenue Line, which opened four years earlier.  It had two tracks and two side platforms, and had connections not only to that station, but also to Myrtle Avenue Line streetcars.  The next southbound stop was Washington Avenue.  The next northbound stop was Franklin Avenue.  The connection to the Lexington Avenue el station lasted until that station closed on October 13, 1950.  Grand Avenue closed on January 21, 1953, while the rest of the line southwest of Broadway was operational until October 4, 1969. Grand Street and Grand Avenue are the respective names of a street which runs through the boroughs of Brooklyn and Queens, New York City, United States.  Originating in Williamsburg, Brooklyn, Grand Street runs roughly northeast until crossing Newtown Creek into Queens, whereupon Grand Street becomes Grand Avenue, continuing through Maspeth where it is a main shopping street, until reaching its northern end at Queens Boulevard in Elmhurst. Myrtle Avenue was a station on the demolished BMT Lexington Avenue Line.  It was opened on May 13, 1885 had two tracks and two side platforms.  It was located at the intersection of Myrtle Avenue and Grand Avenue in Brooklyn, and had connections to Myrtle Avenue Line streetcars.  A segment of the Lexington Avenue Line once ran north from here and turned west on Park Avenue to Hudson Avenue and York Street on its way to the Fulton Ferry until 1891.  The Myrtle Avenue Elevated was built nearby in 1888, and Lexington Avenue Lines trains began to shift onto that line southwest of this station.  It closed on October 13, 1950, although the other BMT station at that location, Grand Avenue was in operation until January 21, 1953, while the rest of the line southwest of Broadway was operational until November 3, 1969.  The next southbound stop was Washington Avenue on the Myrtle Avenue El, but was originally another Washington Avenue station on the Park Avenue El.  The next northbound stop was DeKalb Avenue. 10 was a line operated by the Los Angeles Railway from 1932 to 1946.  At the time of its closure, it ran from Grand Avenue and 39th Street to the intersection of Vernon and Arlington Avenues, by way of Grand Avenue, Santa Barbara Avenue, Dalton Avenue, and Vernon Avenue.  Originally, the route ran all the way to the Edgeware line in Angelino Heights, but this was cut back 1 January 1943.  Why the new terminus was at the seemingly arbitrary intersection of Grand and 39th is unknown. Route 93 is a state highway in the U.S. state of New Jersey.  It is a north–south highway that runs 3.50 mi from an intersection with U.S. Route 1/9 in Ridgefield on Grand Avenue in Ridgefield, Palisades Park, Leonia, and Englewood before ending at an intersection with Van Nostrand Avenue just north of Route 4.  The route originated as Route S5 in 1927, running along the Bergen Turnpike until 1929, when it was moved onto the southern portion of Grand Avenue.  It remained the same until 1954, after the alignment of Route 93 had been designated that the route was extended along Grand Avenue. Grand Street was a railroad station on the Main Line of the Long Island Rail Road.  It stood on Grand Street (now Avenue) in the Elmhurst section of Queens, New York City, west of the present Grand Avenue – Newtown subway station on the IND Queens Boulevard Line.  Though it was only operational for twelve years, it served both the Main Line and the Rockaway Beach Branch which broke away from the main line in Rego Park. Newtown Creek, a 3.5 mi long tributary of the East River, is an estuary that forms part of the border between the boroughs of Brooklyn and Queens, in New York City.  Channelization made it one of the most heavily used bodies of water in the Port of New York and New Jersey and thus one of the most polluted industrial sites in the US, containing years of discarded toxins, an estimated 30000000 USgal of spilled oil, including the Greenpoint oil spill, raw sewage from New York City’s sewer system, and other accumulation from a total of 1,491 sites. The Grand Avenue Water Tower is a water tower located at the intersection of Grand Avenue and 20th street in the College Hill neighborhood of St. Louis, Missouri.  It is the oldest extant water tower in St. Louis, pre-dating both the Bissell Street Water Tower and the Compton Hill Water Tower.
Answer: East River,