About the River

“The Westfield River is recognized as one of the most intact river systems in southern New England, and one of the healthiest tributaries to the Connecticut River. The Westfield River watershed supports a remarkable diversity of common and rare plant and wildlife species, exemplary natural communities, and exceptional scenic and recreational resources. Much of the watershed is rural, with relatively low human population densities and extensive areas of un-fragmented forest. As a result of high ecological integrity and biodiversity significance, several regional conservation planning efforts have identified the Westfield River watershed as among the high priorities for conservation in New England. Active partnerships among a broad range of public agencies, non-profit organizations, and concerned individuals work to conserve the Westfield River watershed, and to identify and mitigate threats to the Westfield River and its tributaries.”

- Excerpt from the Invasive Plant Species on the East Branch and the West Branch of the Westfield River: Management Priorities for Protecting Natural Communities and Rare Species Final Report

Watershed Context

The three branches of the Westfield River: West, Middle and East, rise along the eastern slopes of the Berkshires and the Hilltowns of Western Massachusetts. The three branches flow southward through steep terrain and rural forested communities merging to form the Westfield River in Huntington. From here the river winds its way through urban centers at the southern end of its journey, and finally enters into the Connecticut River in Agawam. In all, the total area draining into the river (a river’s watershed) totals  517 square miles, 636 miles of rivers and streams, as well as over 4550 acres of impoundments, lakes and ponds.

The Westfield River is a major tributary to the Connecticut River and the largest of New England’s river systems. The Westfield River drops 2,000 feet in elevation before entering the Connecticut River. Thin soils in the hills combined with steep gradients produce extreme and rapid differences in the rate of flow, occasional flooding, and at times low water conditions. The river also supports a large cold water fishery with native trout and other cold water dependent river species that thrive in the clean and cool streams and upper segments of the Westfield River. There are vast connected tracts of open space and undeveloped, roadless lands which contribute to the river’s exceptional habitat and water quality while also representing a significant percentage of the state’s aquatic, forested and rare species cores, as assessed and mapped by the Massachusetts Department of Fish & Game (https://biomap-mass-eoeea.hub.arcgis.com/).

The Westfield River watershed is a recovered and recovering landscape. It was almost completely cleared by European settlers by the early 1800s. The Westfield River basin is a US Environmental Protection Agency ecoregional priority within the Lower New England/Northern Piedmont ecoregion, an area that stretches from Maryland to Maine and comprises parts of twelve states. The Nature Conservancy identified several large forest blocks (called matrix forests) on the Berkshire plateau as being among the highest priorities for conservation. The region enables movement of wide-ranging species across the landscape as well as high quality breeding habitat for interior nesting neotropical migrant birds.  These blocks represent the highest quality and least fragmented areas of their kind in the Northeast, and thereby represent biodiversity of global significance.

Because of these remarkable ecological, geologic and cultural attributes, roughly 78 miles of the Westfield River’s three branches, flowing through ten towns, have been designated as a National Wild and Scenic River. The Westfield River was the first Wild & Scenic designation in Massachusetts.

Wildlife Habitat

The Natural Heritage and Endangered Species Program, through its BioMap assessment and mapping program,  identified 32% of the Westfield River watershed as Core Habitat and 76% as Critical Natural Landscape. Core Habitat is the most viable habitat for rare species and natural communities in Massachusetts. Critical Natural Landscape is the essential buffer area that connects and feeds Core Habitat. Critical Natural Landscapes are large, naturally vegetated areas relatively free from the impacts of roads and other development. Subsets of these larger core habitats have also been found in the Wild & Scenic river segments including rare species, aquatic and vernal pool core habitats in frequencies and extent far above those found in other parts of Massachusetts. The upper watershed is also identified as an extensive (85%) regionally connected block mirroring the large tracts of forested lands and minimal road network. There are 21 state-listed rare species intersecting the Wild & Scenic Westfield River segments.

The upper reaches of the watershed offer exceptional habitat for native coldwater species (brook trout, slimy sculpin, longnose dace).  The lower mainstem provides high quality spawning habitat for three species of migratory fish (American shad, blueback herring, and sea lamprey). The Westfield River is a particularly important habitat for shad, hosting one of the largest runs of any Connecticut River tributary. The only known population of the state-endangered lake chub in Massachusetts is found in the upper reaches of the Westfield River and represents the southernmost extent of this species. The Massachusetts Division of Fisheries and Wildlife considers the Westfield River the best example of a diverse fish community in the Commonwealth.

Natural Communities

The Westfield River supports several natural river-dependent communities that are uncommon in Massachusetts and are high priorities for conservation. These include riverside seep and high-terrace floodplain forest natural communities, as well as variants of the high-energy riverbank natural community.

Riverside (Rivershore) Meadows

Rivershore meadow communities extend for several miles along the East Branch, representing the best examples and largest extent of such natural communities observed in Massachusetts (Motzkin et al, 2013).  Rivershore meadows are level to gently sloping communities dominated primarily by perennial graminoid and forb species. Woody species such as silky willow (Salix sericea), silky dogwood (Swida amomum), and glossy buckthorn (Frangula alnus) are often present, but generally not dominant. Vegetation structure and composition vary considerably within rivershore meadows, with some zonation (distinct clusters of species) related to differences in elevation, substrate, frequency of flooding, and degree of ice scour.

Narrow, low-lying areas near the river’s edge and scoured or eroded depressions with moist, mineral substrates are characterized by sparse to moderate cover of low sedges and rushes. Rivershore meadows commonly occur above sparsely vegetated cobble shores. Although frequently flooded during periods of high water, rivershore meadows occur above summer low water levels.

In addition to frequent flooding, rivershore meadows occasionally experience extreme flood events. Tropical Storm Irene in late August 2011 created substantial and variable erosion and deposits across the active floodplain, including the rivershore meadows. Frequent flooding and occasional extreme events like this contribute to the occurrence and persistence of extensive rivershore meadow communities and impact individual rivershore meadows and plant populations.

Riverside Seeps

Riverside seep communities occur occasionally along the banks of the Westfield River in areas where cold groundwater discharges from adjacent slopes onto sites kept open by flooding, ice, or erosion. Groundwater discharge in seeps may be diffuse or concentrated in seepage rivulets. Groundwater flow varies substantially among seeps. Some seeps may dry out during the summer while others flow year-round even in periods of summer drought. Some riverside seeps along the East Branch occur in association with near-surface bedrock, whereas others occur at the base of slopes with deeper soils. In some cases, riverside seeps may develop in areas where groundwater flows over soil hardpan layers (Thompson and Sorenson 2000).

Floodplain Forests

Floodplain forests occur on riverside terraces flooded occasionally during times of high water. Where the river is bounded by steep slopes, floodplain forests are either absent or limited to a narrow band. In areas with more gentle topography, high-terrace floodplain forests occur at elevations above rivershore meadows and riverside seeps, and below the upland woodlands that are protected from flooding even during major storm events.

The Nature Conservancy identified several regionally important floodplain forests including high gradient river floodplain forests along the Westfield River in Huntington and Chester. High gradient river floodplains need relatively higher flow energy/velocity causing scour and disturbance to develop. High gradient floodplains are typically recognized by the presence of either a cobble or gravel river bottom. Re‐sprouting multi‐trunked trees on the riverbanks bent in the downstream direction or have wounds on the upstream side of the trunk as another identifying characteristic.

Thee are two high-gradient river floodplain subtypes: first, a more moderate gradient/energy river where streambeds are gravelly and meandering; second, a higher gradient/energy river with a cobble stream bed and a straighter channel. The two types are combined for the Connecticut River basin because both types share the same dominant species and differ mainly in fluvial geomorphology.

These floodplain forests slow flood waters and reduce soil erosion. The dominant physical processes are frequent flooding typically of short duration and flood disturbance associated with a more extreme event (typically a ten-year reoccurrence interval) and/or ice scour.