Montanye's Rivulet, Manhattan

From Old Wells and Watercourses of the Island of Manhattan, by George Everett Hill and George E. Waring, Jr. in Historic New York: the First Series of the Half Moon Papers (New York, 1899)

    Along the southern edge of The Flats [the area north of 112th Street and east of 8th avenue, approximately] ran a considerable creek, twenty feet deep and one hundred feet wide where it emptied into Hell Gate Bay, near the foot of One hundred and sixth Street. One of its branches rose in the rocks east of Bloomingdale [present site of Columbia University], entered what is now Central Park near the line of One hundred and first Street, then curved northeast and east, and joined the main stream near where One hundred and ninth Street now enters Fifth Avenue. In its course, it flowed through McGowan's Pass, rapidly, but in nothing like so much of a hurry as the stream of redcoats which ran through it, pursued by Washington's troops, after the battle of Harlem Plains. ...to the east, upon Mount St. Vincent and a neighboring elevation, arose, at a later date, Fort Clinton and Fort Fish. This brook was long known as Montanye's Rivulet, and, in the development of Central Park, was used to feed the Pool, the Loch, and Harlem Lake. (p. 363-364)

    Montanye's Rivulet apparently still exists and still feeds the Harlem Lake at least. I don't know if the stream flows partially underground, or if it merely ends at the lake.

For more on the history of McGown's Pass, see the Parks Department page