Saw Mill River
The Saw Mill River is a tributary of the Hudson River in Westchester County, New York, United States. It flows from an unnamed pond north of Chappaqua to Getty Square in Yonkers, where it empties into the Hudson as that river's southernmost tributary. It is the only major stream in southern Westchester County to drain into the Hudson instead of Long Island Sound. It drains an area of, most of it heavily developed suburbia. For, it flows parallel to the Saw Mill River Parkway, a commuter artery, an association that has been said to give the river an "identity crisis."
The watershed was settled by the Dutch in the 17th century. The land was long owned by Frederick Philipse I and his descendants as Philipsburg Manor, site of Philipse Manor Hall, until the family lost it at the end of the American Revolution. The land along the river was later divided into multiple towns. Industry in Yonkers developed along the Saw Mill, so polluting the river by the end of the 19th century that a local poet called it a "snake-like yellow scrawl of scum". In the 1920s, the last half-mile of the stream was routed into culverts under downtown Yonkers, a process partially reversed in the early 21st century when it became the first major New York waterway to be daylighted.
Today, the U.S. Environmental Protection Agency rates the river's last as an impaired water body. Plastics are commonly found along the riverbank, and metals from industrial factories are found in the water in high concentrations. Nonetheless, the river is home to species such as the American eel, which swim upstream to mature and swim back into the Hudson and the ocean in order to breed.
Course
The Saw Mill River rises from a pond in a wooded area of the town of New Castle roughly north of Chappaqua, a west of Quaker Road and just south of Stony Hollow Road, at an elevation of above sea level. It wends in a generally southward direction past a cemetery, between hills, and through an area of houses on large wooded lots. Just north of Marcourt Drive, its first crossing, it is impounded to create another small pond. In this area it is frequently channelized and impounded as part of residential landscaping. After crossing under Kipp Street, it bends eastward beneath Quaker Road.A short channelized portion runs through the front yard of a large house on Quaker southeast of the intersection, after which the river flows back under Quaker and behind the houses on the west side into another impoundment, Chappaqua's Duck Pond. From its outlet it continues southeast between Quaker on its east and Douglas and Mill River roads on the west to the Saw Mill River Parkway. Just west of the Chappaqua train station, it turns southwest to parallel both the parkway and Metro-North Railroad's Harlem Line as both cross into the town of Mount Pleasant. At this point the river is at in elevation, a loss of from its source. Just south of the town line, it receives Tertia Brook, its first named tributary, from the east.
A mile past the town line, the river and parkway pass the village of Pleasantville to the east. There the river crosses under the parkway to flow on its west, then crosses and recrosses at the Pleasantville Road exit. Both make a long turn to the southeast and then back to the southwest around Graham Hills County Park, where it receives Nanny Hagen Brook from the east, before crossing back to the parkway's west in the flood plain around the base of the hills as road, river and rail pass the unincorporated hamlets of Thornwood, and Hawthorne, where the Harlem Line turns to the south.
Just east of the Taconic State Parkway, the river again crosses under the Saw Mill Parkway, then the Taconic. Shortly after that exit it crosses under Saw Mill River Road and some ramps to them from the interchange, then under the Saw Mill Parkway. Both turn south again, then southeast, following the eastern edge of the Pocantico Hills, joined on the west by the North County Trailway bike path, on the right-of-way of the former New York and Putnam Railroad, known as the "Old Put".
The river crosses under the parkway again to form the eastern edge of a plant nursery on Saw Mill River Road, then recrosses as the river, bike path, parkway and Saw Mill River Road all bend around the northwest corner of Eastview, where the Saw Mill drops below in elevation, a loss of since Chappaqua. A turn back to the southwest around Tarrytown Lakes County Park puts the river at the outskirts of Elmsford. There it receives Mine Brook from the east.
Here the bike path ends amidst the dense urban development, but the parkway continues, and the two again draw close as they enter the town of Greenburgh and intersect the Cross Westchester Expressway. A new bike path, the South County Trailway, begins here just south of the West Main Street bridge north of the Rum Brook confluence. Past that the parkway, trailway and the Saw Mill River all turn southwest, where they intersect the New York State Thruway at an oblique angle. For the next mile the Thruway remains close to the river, and Saw Mill River Road, now just carrying NY 9A, returns to the corridor just east of the Thruway as well.
The river then runs along the west of V. Everit Macy Park. As part of the park facilities, the Saw Mill River is impounded into Woodlands Lake, the largest impoundment on the Saw Mill River, used as a water supply by the local communities of Ardsley and Dobbs Ferry, whose northern village line is just to the south. The river runs close to the boundary between the two, as the Thruway gradually veers away to the southeast just past the Ashford Avenue bridge.
Continuing south-southwest, the river along with the parkway and trailway enter Hastings-on-Hudson, its greenbelt the only major break in the village's dense suburban development. It slowly veers toward a more southerly heading, and enters the Nepera Park neighborhood of Yonkers after, just south of Farragut Parkway. Once in the neighborhood, the Saw Mill River flows through a former Yonkers water treatment plant, the other impoundment of the river. After leaving the plant, to the south of where the river entered Yonkers, the parkway and trailway diverge from the river after, to climb over the watershed divide to Tibbetts Brook. Saw Mill River Road continues to parallel its namesake.
Bending to the southwest again, the Saw Mill flows in a narrow channel through an industrial and commercial area. A mile south of the parkway, it flows through the middle of the former Smith Carpet Mills site, where it finally drops to in elevation. After crossing Ashburton Avenue, the river bends around to flow briefly to the northwest under Nepperhan Avenue after crossing the Old Croton Aqueduct. It circles around War Memorial Field, giving up its remaining elevation as the Hudson River nears.
The Saw Mill River turns south again past the park. After passing the towers of a large housing project to its west, it is routed into a tunnel at Chicken Island, the triangle between Nepperhan and Palisade avenues and School Street. At Van der Donck Park in downtown Yonkers, it resurfaces as it flows past the post office. For its final hundred feet, it re-enters a tunnel under the train station and the tracks of the Hudson Line, after which culverts empty it into the Hudson south of Dock Street.
Watershed
The Saw Mill's watershed is limited by the hilly topography of central Westchester County to a valley that averages wide; the only wider spots are the Mine Brook and Tarrytown Lakes subwatersheds and the river's mouth in downtown Yonkers. The highest elevation in the watershed is, reached in two locations: the summit of Sarles Hill north of Pleasantville, and an unnamed height of land about southwest of Buttermilk Hill, west of Hawthorne.From source to mouth, 10% of the watershed is in New Castle, 42% in the town of Mount Pleasant, 33% in Greenburgh, and 14% in Yonkers. 63% of the watershed consists of dense urban or less dense suburban land development, 34% forest, and 1% agricultural. The woodlands buffering the river and the South County Trailway is one of the few significant areas of open space in the county south of I-287.
Some 110,000 people live in the Saw Mill River's watershed, in communities varying from small villages to Yonkers, New York's fourth-largest city. This is 12% of the county's total, on 6% of its area. The watershed's population density varies from 1,000 per square mile around the headwaters at Chappaqua to 10,000 around the mouth. It averages to 4,151 per square mile, twice that of the county and ten times the density for the state.
On the north, the Saw Mill watershed is bordered by the watersheds of Gedney Brook and the Kisco River, both of which drain into New Croton Reservoir on the Croton River, one of several large reservoirs in that watershed that are part of New York City's water supply system. On the northeast, the adjacent watersheds drain into Kensico Reservoir, another that supplies the city. Moving south, the next watersheds are tributaries of the Bronx River, then Yonkers' Grassy Sprain Reservoir and finally Tibbetts Brook. To its west in the narrow strip between the Saw Mill and the Hudson are the Pocantico River and Sheldon Brook watersheds at the north end of the watershed, and those of unnamed shorter streams at the south.