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108-781: The Saw Mill River is a 23.5-mile (37.8 km) 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 26.5 square miles (69 km), most of it heavily developed suburbia. For 16 miles (26 km), it flows parallel to

216-447: A Yonkers sugar refinery spilled hydrochloric acid into the river. Westchester District Attorney Jeanine Pirro brought criminal environmental charges against American Sugar Refining , the plant owner, which was forced to pay a $ 20,000 fine; make a $ 100,000 donation to Riverkeeper , a regional environmental organization that focuses on the Hudson and its tributaries; and give 1 short ton (910 kg) of sugar to Westchester Food-PATCH,

324-666: A century later, residents named their hamlet after the remark, "Elmsford". He left a meeting at the Hammond House in Eastview moments before Loyalists converged on it; his host, Col. James Hammond, the commander of the Westchester militia, was captured and imprisoned for the rest of the war. On the British side, Major John André spent his last night before his capture, with documents exposing Benedict Arnold 's betrayal, at

432-457: A day from the river through this system. Despite this, the pollution of the river continued unabated, reversing its earlier recovery. In a 1920 report on the condition of public water supplies around the state, New York's Health Department said "sanitary conditions upon the Saw Mill watershed are very unsatisfactory", despite the considerable rules and regulations it had promulgated to protect

540-554: A flood-prone property to qualify for government-subsidized insurance, a local community must adopt an ordinance that protects the floodway and requires that new residential structures built in Special Flood Hazard Areas be elevated to at least the level of the 100-year flood. Commercial structures can be elevated or floodproofed to or above this level. In some areas without detailed study information, structures may be required to be elevated to at least two feet above

648-445: A floodplain. The quantity of sediments in a floodplain greatly exceeds the river load of sediments. Thus, floodplains are an important storage site for sediments during their transport from where they are generated to their ultimate depositional environment. When the rate at which the river is cutting downwards becomes great enough that overbank flows become infrequent, the river is said to have abandoned its floodplain. Portions of

756-473: A lake wide enough to slow any British progress up the river. At Chappaqua, the pacifist Quakers opened their meetinghouse as a hospital for injured Continental Army soldiers. Storm's tavern was a gathering place for Continental officers and, later, their French colleagues . As one of the few routes into hilly central Westchester, the river and its associated roads saw frequent skirmishes. In November 1777, three young men with Patriot sympathies were walking near

864-555: A local nonprofit that supplies food to other nonprofits. Riverkeeper passed the money it received along to the Saw Mill River Coalition for local projects in Yonkers. In 2008, Groundwork Hudson Valley, the coordinator of the Saw Mill River Coalition, received a three-year, $ 889,183 U.S. Environmental Protection Agency Targeted Watershed Grant. One of 15 recipients from a nationwide pool of more than 100 applicants,

972-507: A lovely valley, shrouded by groves, and dotted by Dutch farm-houses, empties itself into the Hudson, at the ancient drop of Yonkers. – Washington Irving , Wolfert's Roost , Chronicle II 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

1080-619: A midnight raid on Storm's Bridge. Hoping to capture Storm and his cousins the Van Tassels, all active in the local Patriot militia, the Chasseurs settled for burning and looting Storm's house and tavern. Proceeding on to the Van Tassel houses, they trapped Cornelius Van Tassel Jr., one of the cousins' teenage sons. As the Chasseurs set fire to the houses, he hid on a roof, then jumped off, fended off some putative captors, and fled into

1188-400: A new river, to be given its own name, perhaps one already known to the people who live upon its banks. Conversely, explorers approaching a new land from the sea encounter its rivers at their mouths, where they name them on their charts, then, following a river upstream, encounter each tributary as a forking of the stream to the right and to the left, which then appear on their charts as such; or

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1296-438: A residential area of houses on large wooded lots in a generally southward direction. 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 the landscaping on the area's large residential land lots . After crossing under Kipp Street, it bends eastward to cross under Quaker Road. A short channelized portion runs through

1404-597: A tavern at the junction of the Saw Mill River and Tarrytown roads (today routes 9A and 119 ) that is the center of that village today. In 1719, one of the Philipse tenant farmers, William Hammond, built his house on land he leased in what is today Eastview , where his house still stands. Along the river to the north, his brother Staats Hammond built two mills along the river; the small settlement of Hammond's Mill became today's Hawthorne . Other settlers came to

1512-506: 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

1620-546: Is a problem in freshwater systems. Much of the phosphorus in freshwater systems comes from municipal wastewater treatment plants and agricultural runoff. Stream connectivity controls whether phosphorus cycling is mediated by floodplain sediments or by external processes. Under conditions of stream connectivity, phosphorus is better able to be cycled, and sediments and nutrients are more readily retained. Water in freshwater streams ends up in either short-term storage in plants or algae or long-term in sediments. Wet/dry cycling within

1728-406: Is advantageous for the rapid colonization of large areas of the floodplain. This allows them to take advantage of shifting floodplain geometry. For example, floodplain trees are fast-growing and tolerant of root disturbance. Opportunists (such as birds) are attracted to the rich food supply provided by the flood pulse. Floodplain ecosystems have distinct biozones. In Europe, as one moves away from

1836-498: Is any area subject to inundation by a 100-year flood. A problem is that any alteration of the watershed upstream of the point in question can potentially affect the ability of the watershed to handle water, and thus potentially affects the levels of the periodic floods. A large shopping center and parking lot, for example, may raise the levels of 5-year, 100-year, and other floods, but the maps are rarely adjusted and are frequently rendered obsolete by subsequent development. In order for

1944-460: Is described as vertical accretion , since the deposits build upwards. In undisturbed river systems, overbank flow is frequent, typically occurring every one to two years, regardless of climate or topography. Sedimentation rates for a three-day flood of the Meuse and Rhine Rivers in 1993 found average sedimentation rates in the floodplain of between 0.57 and 1.0 kg/m . Higher rates were found on

2052-530: 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

2160-565: Is largely a result of flood control, hydroelectric development (such as reservoirs), and conversion of floodplains to agriculture use. Transportation and waste disposal also have detrimental effects. The result is the fragmentation of these ecosystems, resulting in loss of populations and diversity and endangering the remaining fragments of the ecosystem. Flood control creates a sharper boundary between water and land than in undisturbed floodplains, reducing physical diversity. Floodplain forests protect waterways from erosion and pollution and reduce

2268-402: Is most common in sections of rivers where the river bed is accumulating sediments ( aggrading ). Repeated flooding eventually builds up an alluvial ridge, whose natural levees and abandoned meander loops may stand well above most of the floodplain. The alluvial ridge is topped by a channel belt formed by successive generations of channel migration and meander cutoff. At much longer intervals,

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2376-587: 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

2484-595: The National Register of Historic Places in 1974. As tensions rose between the colonists and Britain in the early 1770s, Philipse remained loyal to the crown. He was arrested in August 1776 and held in Connecticut until a parole grant at the end of the year allowed him to return home as long as he did nothing to support the British war effort. He broke that promise the next spring: he attempted, perhaps at

2592-477: The New York State Thruway later in the decade, required some adjustment of the river's course in some areas. Westchester's postwar development led to more stormwater runoff , which often flooded and closed the parkway. By 1958, engineers were urging that the river be cleaned up to reduce flooding. Still, illegal dumping and overflows continued. For example, storm runoff gave the Yonkers section

2700-577: The North County Trailway north of 119 in Elmsford. To slake the thirst of its ever-growing population, which had reached almost 100,000 by 1915, Yonkers tapped the Saw Mill. Water from an impoundment 2 miles (3.2 km) north of downtown was held in two reservoirs and two water towers. It was purified by slow filtration through sand and then chlorinated . By 1919 the city was drawing an average of 10.6 million gallons (40,000 m)

2808-596: 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

2916-466: The U.S. Environmental Protection Agency (EPA) rates the river's last 2.9 miles (4.7 km) 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 (Anguilla rostrata), which swim upstream to mature and swim back into the Hudson and

3024-557: The Yellow River in China – see list of deadliest floods . The worst of these, and the worst natural disaster (excluding famine and epidemics), was the 1931 China floods , estimated to have killed millions. This had been preceded by the 1887 Yellow River flood , which killed around one million people and is the second-worst natural disaster in history. The extent of floodplain inundation depends partly on flood magnitude, defined by

3132-747: The return period . In the United States, the Federal Emergency Management Agency (FEMA) manages the National Flood Insurance Program (NFIP). The NFIP offers insurance to properties located within a flood-prone area, as defined by the Flood Insurance Rate Map (FIRM), which depicts various flood risks for a community. The FIRM typically focuses on the delineation of the 100-year flood inundation area, also known within

3240-599: The town of Greenburgh , in which the entire eastern half of the tract had been located. The towns of Yonkers and Mount Pleasant joined Greenburgh, all approximately within their present boundaries. In 1790, a group of settlers organized the Greenburgh Presbyterian Church, and three years later built a church at Storm's Bridge. (Today, it is the National Register-listed Elmsford Reformed Church ,

3348-623: 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

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3456-691: 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 ( State Routes 9A and 100 ) and some ramps to them from the interchange, then under the Saw Mill Parkway. Both turn south again, then southeast, following

3564-426: The 320 acres (130 ha) around the manor house. Wells neither subdivided nor developed the property, although he did extensively landscape the manor house grounds. In 1831, Wells built a long wharf into the Hudson just above the mouth of the Saw Mill for the steamboat service which had been established between New York and Albany . Otherwise, the property remained largely unchanged until his death in 1842. Maps of

3672-491: The British, who raised a force of about 100 cavalry and 400 to 500 infantry at Fort Washington , today on the northern tip of Manhattan . The force marched to Yonkers and up the Saw Mill overnight, arriving at Four Corners the next morning. The outnumbered Continentals put up stiff resistance, aided by the cold, heavy snow cover and their opponents' fatigue, but most were ultimately killed or taken prisoner. The British and their Loyalist and Hessian allies celebrated by burning down

3780-700: The Cross Westchester Expressway ( Interstate 287 ). A new bike path, the South County Trailway , begins here just south of the West Main Street ( State Route 119 ) 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 ( Interstate 87 ) at an oblique angle. For the next mile the Thruway remains close to

3888-640: The Manhattans the area that would become Yonkers. Seven years later, Dutch settler Adriaen van der Donck was granted part of this land, including the southern section of what he named the Saeck-kill , today's Saw Mill River. His estate was called Colen Donck, for "Donck's colony". He built a sawmill and a gristmill on the Saeck-kill. After his death, his widow gradually sold the land. In the 1670s, part of Donck's land passed to Frederick Philipse , who

3996-534: The Mine Brook and Tarrytown Lakes subwatersheds and the river's mouth in downtown Yonkers. The highest elevation in the watershed is 710 feet (220 m), reached in two locations: the summit of Sarles Hill north of Pleasantville, and an unnamed height of land about 1,200 feet (370 m) southwest of Buttermilk Hill , west of Hawthorne. From source to mouth, 10% of the watershed is in New Castle , 42% in

4104-560: The NFIP as the Special Flood Hazard Area. Where a detailed study of a waterway has been done, the 100-year floodplain will also include the floodway, the critical portion of the floodplain which includes the stream channel and any adjacent areas that must be kept free of encroachments that might block flood flows or restrict storage of flood waters. Another commonly encountered term is the Special Flood Hazard Area, which

4212-485: The Nepera Park neighborhood of Yonkers after 1 mile (1.6 km), 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, 1.5 miles (2.4 km) to the south of where the river entered Yonkers, the parkway and trailway diverge from the river after 16 miles (26 km), to climb over

4320-596: The Rookery inn in Hawthorne. Later in the war, Young's farmhouse and Four Corners were the site of the largest military engagement near the river. By 1780, the Continentals were operating much more freely around northern Westchester, although they had to stay on the move to avoid attack. In January, one company of about 250 troops from Massachusetts lingered long enough at Four Corners for local Loyalists to inform

4428-583: The Saw Mill River's headwaters from a different direction. Quakers had been immigrating to Long Island since the previous century to escape religious persecution in England; in the 1700s, "Shapequaw", north of the present hamlet of Chappaqua, was established. In the middle of the century, the community built its meeting house ; it and other buildings of the era are today part of the Old Chappaqua Historic District , listed on

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4536-780: 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. The Saw Mill River, then known as the Nepperhan River, acted as a boundary between the Manhattan Indians and the Weckquaesgeeks , members of the Algonquian family who fished the region's streams and lakes with rods and nets. The Manhattans occupied present-day New York City north to

4644-437: The Saw Mill drops below 200 feet (61 m) in elevation, a loss of 100 feet (30 m) 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

4752-538: The Young house; the Continentals retreated to the north of the Croton River for the rest of the war. In 1779, the New York State Legislature passed a bill of attainder confiscating the property of British officials and prominent Loyalists, Philipse included. The land, including land in the Saw Mill River watershed, was then distributed to the tenant farmers. In 1788, the state divided into three

4860-400: The abandoned floodplain may be preserved as fluvial terraces . Floodplains support diverse and productive ecosystems . They are characterized by considerable variability in space and time, which in turn produces some of the most species-rich of ecosystems. From the ecological perspective, the most distinctive aspect of floodplains is the flood pulse associated with annual floods, and so

4968-511: The advantages provided by the richness of the alluvial soil of the floodplain are severely offset by frequent floods brought on by cyclones and annual monsoon rains. These extreme weather events cause severe economic disruption and loss of human life in the densely-populated region. Floodplain soil composition is unique and varies widely based on microtopography. Floodplain forests have high topographic heterogeneity which creates variation in localized hydrologic conditions. Soil moisture within

5076-692: The behest of his wife, to inform the British that a passing column of Continental Army troops was headed south to attack a British camp at Morrisania , now in the Bronx. Shortly afterwards he fled to British-occupied New York; he would never return to his home along the Saw Mill. Communities along the Saw Mill played minor parts in the Revolutionary War , especially after the Battle of White Plains in October 1776. The defeated Continentals retreated to

5184-467: The channel shifts varies greatly, with reported rates ranging from too slow to measure to as much as 2,400 feet (730 m) per year for the Kosi River of India. Overbank flow takes place when the river is flooded with more water than can be accommodated by the river channel. Flow over the banks of the river deposits a thin veneer of sediments that is coarsest and thickest close to the channel. This

5292-509: The cold waters of the nearby Saw Mill. He got away, but soon died of hypothermia . The Saw Mill River and its adjacent terrain conferred some tactical advantages to those who knew it. One skirmish began when a Patriot militiaman, Jake Acker, was hunting in a bushy area of the eastern flood plain at Elmsford. Spying a large group of British soldiers and Loyalist supporters on the road to Storm's tavern, Acker began sniping at them from his concealment. He fatally wounded one, changed his position amid

5400-516: The construction of the Hudson River Railroad in 1848, which laid its track on a causeway right across the river's mouth. Over the next several decades, as Yonkers' population grew rapidly, leading it to incorporate as a village and then, in 1872, a city, the rest of the estuary was filled in and narrowed and the bluffs on its south side graded out of existence. By the later decades of the 19th century, industry had grown up along

5508-468: The distraction, reloaded his musket, and killed another. Hearing the shots, other local Patriots came to Acker's aid, and eventually all but one of the larger force were killed or captured. Some senior Continental Army officers spent time in the Saw Mill River valley. George Washington is said to have mentioned the " ford over the Nepperhan at the elm tree ", referring to a wide tree no longer extant;

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5616-501: The east. There the river crosses under the parkway to flow on its west, then crosses and recrosses at the Pleasantville Road ( State Route 117 ) 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

5724-503: 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

5832-529: The first-order tributary being typically the least in size. For example, a second-order tributary would be the result of two or more first-order tributaries combining to form the second-order tributary. Another method is to list tributaries from mouth to source, in the form of a tree structure , stored as a tree data structure . Flood plain Because of regular flooding, floodplains frequently have high soil-fertility since nutrients are deposited with

5940-472: The flood waters. This can encourage farming ; some important agricultural regions, such as the Nile and Mississippi river basins , heavily exploit floodplains. Agricultural and urban regions have developed near or on floodplains to take advantage of the rich soil and freshwater. However, the risk of inundation has led to increasing efforts to control flooding . Most floodplains are formed by deposition on

6048-448: The floodplain ecosystem is defined as the part of the river valley that is regularly flooded and dried. Floods bring in detrital material rich in nutrients and release nutrients from dry soil as it is flooded. The decomposition of terrestrial plants submerged by the floodwaters adds to the nutrient supply. The flooded littoral zone of the river (the zone closest to the river bank) provides an ideal environment for many aquatic species, so

6156-462: The floodplain has a big impact on phosphorus availability because it alters water level, redox state, pH, and physical properties of minerals. Dry soils that were previously inundated have reduced availability of phosphorus and increased affinity for obtaining phosphorus. Human floodplain alterations also impact the phosphorus cycle. Particulate phosphorus and soluble reactive phosphorus (SRP) can contribute to algal blooms and toxicity in waterways when

6264-599: The floodplain. Other smaller-scale mitigation efforts include acquiring and demolishing flood-prone buildings or flood-proofing them. In some floodplains, such as the Inner Niger Delta of Mali , annual flooding events are a natural part of the local ecology and rural economy , allowing for the raising of crops through recessional agriculture . However, in Bangladesh , which occupies the Ganges Delta ,

6372-486: 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

6480-400: The group cleans up garbage, removes invasive species, and plants native trees along the river. The group also marks storm drains that drain to the river. On September 25–26, 2009, the Saw Mill River Coalition organized a BioBlitz to catalog species of plant life, animal life, insects, fungi, and bacteria in the river and its watershed. The Coalition is also looking to restore the wetlands along

6588-451: The handedness is from the point of view of an observer facing upstream. For instance, Steer Creek has a left tributary which is called Right Fork Steer Creek. These naming conventions are reflective of the circumstances of a particular river's identification and charting: people living along the banks of a river, with a name known to them, may then float down the river in exploration, and each tributary joining it as they pass by appears as

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6696-465: The impact of floodwaters. The disturbance by humans of temperate floodplain ecosystems frustrates attempts to understand their natural behavior. Tropical rivers are less impacted by humans and provide models for temperate floodplain ecosystems, which are thought to share many of their ecological attributes. Excluding famines and epidemics , some of the worst natural disasters in history (measured by fatalities) have been river floods, particularly in

6804-448: The inside of river meanders and by overbank flow. Wherever the river meanders, the flowing water erodes the river bank on the outside of the meander. At the same time, sediments are simultaneously deposited in a bar on the inside of the meander. This is described as lateral accretion since the deposition builds the point bar laterally into the river channel. Erosion on the outside of the meander usually closely balances deposition on

6912-417: The inside so that the channel shifts in the direction of the meander without changing significantly in width. The point bar is built up to a level very close to that of the river banks. Significant net erosion of sediments occurs only when the meander cuts into higher ground. The overall effect is that, as the river meanders, it creates a level flood plain composed mostly of point bar deposits. The rate at which

7020-424: The joining of tributaries. The opposite to a tributary is a distributary , a river or stream that branches off from and flows away from the main stream. Distributaries are most often found in river deltas . Right tributary , or right-bank tributary , and left tributary , or left-bank tributary , describe the orientation of the tributary relative to the flow of the main stem river. These terms are defined from

7128-518: The late 19th century, the New York and Putnam Railroad was built along the Saw Mill River from Putnam County to central Yonkers, and thence to Tibbets Creek and the Harlem River . Various parts of the line operated until the 1940s and the 1980s. The main line of the railroad is now devoted to bicycle and pedestrian paths. They are the South County Trailway on the parts south of Route 119, and

7236-457: The levees (4 kg/m or more) and on low-lying areas (1.6 kg/m ). Sedimentation from the overbank flow is concentrated on natural levees, crevasse splays , and in wetlands and shallow lakes of flood basins. Natural levees are ridges along river banks that form from rapid deposition from the overbank flow. Most of the suspended sand is deposited on the levees, leaving the silt and clay sediments to be deposited as floodplain mud further from

7344-617: The makeup towards ash (49%) with maple increasing to 14% and oak decreasing to 25%. Semiarid floodplains have a much lower species diversity. Species are adapted to alternating drought and flood. Extreme drying can destroy the ability of the floodplain ecosystem to shift to a healthy wet phase when flooded. Floodplain forests constituted 1% of the landscape of Europe in the 1800s. Much of this has been cleared by human activity, though floodplain forests have been impacted less than other kinds of forests. This makes them important refugia for biodiversity. Human destruction of floodplain ecosystems

7452-469: The manor was divided between his son Adolph and grandson Frederick II. In 1750, his great-grandson Frederick III inherited the whole property and moved from his New York City townhouse to the manor hall, previously used as the family's summer home. Frederick sat in the Colonial Assembly, where he was a strong supporter of the British government that had given his family everything it owned, but he

7560-762: The nitrogen-to-phosphorus ratios are altered farther upstream. In areas where the phosphorus load is primarily particulate phosphorus, like the Mississippi River, the most effective ways of removing phosphorus upstream are sedimentation, soil accretion, and burial. In basins where SRP is the primary form of phosphorus, biological uptake in floodplain forests is the best way of removing nutrients. Phosphorus can transform between SRP and particulate phosphorus depending on ambient conditions or processes like decomposition, biological uptake, redoximorphic release, and sedimentation and accretion. In either phosphorus form, floodplain forests are beneficial as phosphorus sinks, and

7668-425: The ocean in order to breed. The Saw Mill River rises from a 1.75-acre (7,100 m) pond in a wooded area of the town of New Castle roughly 2 miles (3.2 km) north of Chappaqua, a one-half mile (800 m) west of Quaker Road State Route 120 (NY 120) and just south of Stony Hollow Road, at an elevation of 490 feet (150 m) above sea level. It wends and meanders past a cemetery, between hills, through

7776-507: The oldest building in the village, the oldest church in continuous use in Westchester County.) Most of Yonkers' economy in the early 19th century was derived from the Saw Mill River. As of 1813, there was a small wharf slightly upstream from the mouth where the sloops that carried river trade put in. Five small mills existed along the river above the village, all with their own dams, small mill ponds , and nearby tenements for

7884-406: The opposite bank before approaching the confluence. An early tributary is a tributary that joins the main stem river closer to its source than its mouth, that is, before the river's midpoint ; a late tributary joins the main stem further downstream, closer to its mouth than to its source, that is, after the midpoint. In the United States, where tributaries sometimes have the same name as

7992-409: The other's sympathizers and supporters. Many residents of southern Westchester abandoned their farms and drove their herds up the valley to Buttermilk Hill to protect them from Loyalist raids. The Continentals built forts near Hawthorne, where a minor tributary named Flykill Creek drained into the Saw Mill (roughly at the junction of today's Saw Mill and Taconic parkways), and built Yankee Dam to create

8100-420: 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 340 feet (100 m) in elevation, a loss of 150 feet (46 m) 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 its eponymous parkway pass the village of Pleasantville to

8208-476: The perspective of looking downstream, that is, facing the direction the water current of the main stem is going. In a navigational context, if one were floating on a raft or other vessel in the main stream, this would be the side the tributary enters from as one floats past; alternately, if one were floating down the tributary, the main stream meets it on the opposite bank of the tributary. This information may be used to avoid turbulent water by moving towards

8316-472: The post office . For its final hundred feet (30 m), 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. The Saw Mill's 26.5-square-mile (69 km) watershed is limited by the hilly topography of central Westchester County to a valley that averages 1.4 miles (2.3 km) wide; the only wider spots are

8424-523: The present Glenwood without setting his foot upon the ground".) Between the rocky soil and Wells' general refusal to sell or lease most of his land, there were so few settlers in Yonkers that two schoolhouses built during the Revolution fell into severe neglect due to the lack of students. The manor house and the surrounding land at the river's mouth that is today downtown passed through several owners until 1813, when New York merchant Lemuel Wells bought

8532-474: The property from the time of Wells' purchase and his death show the Saw Mill's mouth widening into a small estuary before reaching the Hudson. The south bank of the river at the mouth had a 40-foot-high (12 m) bluff. The only construction directly affecting the river was the bridge that carried the Albany Post Road , today Riverdale and Warburton avenues, part of U.S. Route 9 and Route 9A, over

8640-713: 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. As every one may not recognize these boundaries by their original Indian names, it may be well to observe, that the Neperan is that beautiful stream, vulgarly called the Saw-Mill River, which, after winding gracefully for many miles through

8748-631: The river crossing on the Dobbs Ferry Road (now Ashford Avenue) when they came upon a group of horsemen affiliated with Kipp's Regiment, one of the county's most-feared Loyalist militias. The young men taunted their rivals, who beat them so severely that two later died. The survivor was awarded a pension , believed to be the first in U.S. history, by the Continental Congress . Later that month, Emmerich's Chasseurs, an elite unit of Loyalist militia and Hessian mercenaries, staged

8856-564: The river for six blocks in Downtown Yonkers. The newly surfaced river is the centerpiece of an urban park in Getty Square , Downtown Yonkers. Tributary A tributary , or an affluent , is a stream or river that flows into a larger stream ( main stem or "parent" ), river, or a lake . A tributary does not flow directly into a sea or ocean . Tributaries, and the main stem river into which they flow, drain

8964-436: The river in Yonkers. The city's own public works department had noted dozens of violations for the previous year, most of them continued from the years before that. "A great many privies and cesspools are located on the edge of the Saw Mill and its tributaries and there is also drainage from poultry yards, barnyards and house drains," the department noted Rather than enforce the violated regulations more strictly and clean up

9072-472: The river in order to reduce flooding. Raising of the Saw Mill Parkway continues; in 2013, a 900-foot (270 m) stretch in Pleasantville was raised by three inches to reduce flooding from the river. The city of Yonkers carried out a $ 48 million daylighting project in the 2010s to remove the culvert that the river flows through under Yonkers and bring the river to the surface. The project uncovered

9180-666: The river into which they feed, they are called forks . These are typically designated by compass direction. For example, the American River in California receives flow from its North, Middle, and South forks. The Chicago River 's North Branch has the East, West, and Middle Fork; the South Branch has its South Fork, and used to have a West Fork as well (now filled in). Forks are sometimes designated as right or left. Here,

9288-580: The river may abandon the channel belt and build a new one at another position on the floodplain. This process is called avulsion and occurs at intervals of 10–1000 years. Historical avulsions leading to catastrophic flooding include the 1855 Yellow River flood and the 2008 Kosi River flood . Floodplains can form around rivers of any kind or size. Even relatively straight stretches of river are capable of producing floodplains. Mid-channel bars in braided rivers migrate downstream through processes resembling those in point bars of meandering rivers and can build up

9396-405: The river were established during the colonial era. In 1695, a land agent named Isaac See settled at the north bound of Philipse Manor, in the flat land between a bend in the river. Other farmers came to the area, and the settlement ultimately became today's village of Pleasantville . By 1704, the area that is today Elmsford, New York was known as Storm's Bridge, after Abraham Storm, who established

9504-516: The river's highest concentrations of heavy metals, PCBs, and other chemicals, according to a study of the river in 1983, the year the city stopped using the Saw Mill as its primary water source. A decade later, the sediment in the Saw Mill had the highest concentration of metals in the United States Geological Survey 's entire water-quality assessment program. A new kind of pollution entered the lower Saw Mill in 2003 when

9612-542: The river's lower portion. So much pollution was dumped into the river from the factories alongside it that a local poet lamented the Saw Mill's decline in an 1891 quatrain : ' Tis now, at Yonkers's spreading feet, A flow with odorous sins replete ; Its nitid bosom has become A snake-like yellow scrawl of scum. To let the river replenish itself, most of the dams that had been built were removed in 1893. Ten years later it had somewhat recovered, and people were again using it for drinking water and swimming. In

9720-425: 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

9828-508: The river, just as the 1922 Bronx River Parkway follows the Bronx River , and to add a sewer line along the river to prevent contamination of Yonkers' water supply. Construction began in 1929 and continued throughout the Great Depression . By 1940, the parkway had reached the river's headwaters at Chappaqua, where World War II temporarily halted construction. In 1954, it was complete. The parkway's construction, along with that of

9936-429: The river, the city chose to cover it up entirely. Between 1917 and 1922, the last 2,000 feet (610 m) of river, including a small gorge , was buried in a culvert under the Getty Square neighborhood, an effort to halt the river's frequent floods and quarantine its unsanitary water, and open up some space for further development. That same decade, the county parks commission proposed the Saw Mill River Parkway along

10044-511: The river, the successive plant communities are bank vegetation (usually annuals); sedge and reeds; willow shrubs; willow-poplar forest; oak-ash forest; and broadleaf forest. Human disturbance creates wet meadows that replace much of the original ecosystem. The biozones reflect a soil moisture and oxygen gradient that in turn corresponds to a flooding frequency gradient. The primeval floodplain forests of Europe were dominated by oak (60%) elm (20%) and hornbeam (13%), but human disturbance has shifted

10152-614: The river, while the Weckquaesgeeks occupied the land from the river north to the Pocantico River. The Manhattans' principal village, Nepperamack, was on the site of present-day Yonkers where the Saw Mill River discharges into the Hudson River. The Weckquaesgeeks settled the site of today's Dobbs Ferry, and on the river's banks west of White Plains . In 1639, the Dutch West India Company acquired from

10260-451: The river. Wells had survived the death of his first wife and all four of his brothers; he also had no children, leaving him without a clear heir. His estate was further complicated by his lack of a will . Accordingly, under New York law at the time, his holdings were divided among his widow, fifteen nephews and one grand nephew. They decided to subdivide and sell the property, and within a few years more buildings had gone up, just in time for

10368-418: The river. Levees are typically built up enough to be relatively well-drained compared with nearby wetlands, and levees in non-arid climates are often heavily vegetated. Crevasses are formed by breakout events from the main river channel. The river bank fails, and floodwaters scour a channel. Sediments from the crevasse spread out as delta -shaped deposits with numerous distributary channels. Crevasse formation

10476-418: The smaller stream designated the little fork, the larger either retaining its name unmodified, or receives the designation big . Tributaries are sometimes listed starting with those nearest to the source of the river and ending with those nearest to the mouth of the river . The Strahler stream order examines the arrangement of tributaries in a hierarchy of first, second, third and higher orders, with

10584-408: The spawning season for fish often coincides with the onset of flooding. Fish must grow quickly during the flood to survive the subsequent drop in water level. As the floodwaters recede, the littoral experiences blooms of microorganisms, while the banks of the river dry out and terrestrial plants germinate to stabilize the bank. The biota of floodplains has high annual growth and mortality rates, which

10692-432: The streams are seen to diverge by the cardinal direction (north, south, east, or west) in which they proceed upstream, sometimes a third stream entering between two others is designated the middle fork; or the streams are distinguished by the relative height of one to the other, as one stream descending over a cataract into another becomes the upper fork, and the one it descends into, the lower ; or by relative volume:

10800-547: The surrounding drainage basin of its surface water and groundwater , leading the water out into an ocean. The Irtysh is a chief tributary of the Ob river and is also the longest tributary river in the world with a length of 4,248 km (2,640 mi). The Madeira River is the largest tributary river by volume in the world with an average discharge of 31,200 m /s (1.1 million cu ft/s). A confluence , where two or more bodies of water meet, usually refers to

10908-459: The surrounding grade. Many State and local governments have, in addition, adopted floodplain construction regulations which are more restrictive than those mandated by the NFIP. The US government also sponsors flood hazard mitigation efforts to reduce flood impacts. California 's Hazard Mitigation Program is one funding source for mitigation projects. A number of whole towns such as English, Indiana , have been completely relocated to remove them from

11016-672: The upper 30 cm of the soil profile also varies widely based on microtopography which affects oxygen availability. Floodplain soil stays aerated for long stretches of time in between flooding events, but during flooding, saturated soil can become oxygen-depleted if it stands stagnant for long enough. More soil oxygen is available at higher elevations farther from the river. Floodplain forests generally experience alternating periods of aerobic and anaerobic soil microbe activity which affects fine root development and desiccation. Floodplains have high buffering capacity for phosphorus to prevent nutrient loss to river outputs. Phosphorus nutrient loading

11124-538: The vicinity of Peekskill while the victorious British withdrew to Kingsbridge in what is now the Bronx . Neither side wanted to cede control of the Hudson Valley , which divided New England from the other colonies. This left most of Westchester unoccupied neutral ground . However, Westchester was not demilitarized . Local militias and raiding parties affiliated with both sides fought each other and terrorized

11232-405: 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 100 feet (30 m) in elevation. After crossing Ashburton Avenue,

11340-458: The workers. The stagecoach route up the Post Road stopped at an inn near the bridge; a few stores existed to supply the workers there and at the mills. Some pastures and orchards existed, but the rocky soil deterred most attempts at farming. (A historian later wrote that it was said at the time that "the succession of boulders was so continuous that one might have stepped from Getty Square to

11448-460: 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 (800 m) of the stream was routed into tunnels and 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,

11556-432: Was primarily interested in managing the land. He improved the manor hall and worked to attract tenant farmers to the land. The family was known for its relaxed approach to its tenants, and the farm was very profitable. Commercially navigable only at its mouth, the Saw Mill River itself was useless as a way to bring crops to market, limiting settlement further upriver. Nevertheless, the roots of present-day communities along

11664-412: Was rewarded with 90,000 acres (360 km), including the lower river, for declaring his loyalty to the new British rulers of New Netherlands . Philipse named the manor Philipsborough and ran it as a quasi-feudal farm, hiring tenants to work the land. Around 1682, he built Philipse Manor Hall , a mansion along the Saw Mill River that is today a National Historic Landmark . When Philipse died around 1702,

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