Furnace Brook, in Cortlandt, is another small tributary of the Hudson. Pocantico River, rising in New Castle, forms the dividing line between Ossining and Mount Pleasant, and through Sleepy Hollow, finds its outlet in the Hudson at Tarrytown. Neperhan, or Saw-Mill River, rises in New Castle, and flowing through Mount Pleasant, Greenburgh and Yonkers, discharges its waters into the Hudson at the city of Yonkers. Tibbitts' Brook, a small stream in Yonkers, empties into the Spuyten Duyvil Creek.

The streams which find their outlet in the Sound are: The Bronx River, which rises in the hills of Mount Pleasant, and North Castle, and flowing southerly, drains a large portion of the southern -middle section of the county. The Westchester Creek, a tidal stream, drains a small pari of the southern end of the county and empties into Westchester Bay, an estuary of the Sound. Hutchinson River, rising in Scarsdale, flows southward into Eastchester Bay, on the Sound. Mamaroneck River^ rising near White Plains and Harrison, flows into Mamaroneck Harbor, on the Sound. Byram River and Blind Brook are streams which also discharge their waters into the Sound, the former at Port Chester, after draining portions of Bedford, North Castle and Rye, and the latter at Milton, after draining portions of Harrison and Rye. The Maharness, rising in North Castle, and Stamford Mill River, rising in Poundridge, flow into Connecticut and thence to the Sound.

The southern or Sound shore of the county is indented with bays and estuaries, of which Westchester or Pelham Bay and Mamaroneck Harbor are the largest. Peninsulas stretch out into the Sound, of which Throgg's Neck, Pelham's Neck, Davenport's Neck and DeLancey's Neck are the most important. Islands are ntimerous along the shore of the Sound. The largest are City, Hunter's, David's, Huckleberry and Manaessing Islands.