IBA Chehalis River Estuary
Chilliwack, British Columbia
Site Summary
BC033 Latitude
49.276° N
121.926° W
10 - 20 m
31.98 km²
deciduous woods (temperate), mixed woods (temperate), rivers/streams, freshwater marsh
Land Use:
Agriculture, Nature conservation and research, Forestry, Hunting, Rangeland/pastureland
Potential or ongoing Threats:
Deforestation, Fisheries, Recreation/tourism, Urban/industrial development
IBA Criteria: Globally Significant: Congregatory Species
Conservation status: Wild Bird Trust of British Columbia
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Site Description
This site is located where the Chehalis River empties into the lower Harrison River, just upstream from its junction with the Fraser River. The town of Harrison Mills is nearby, and Chilliwack is about 10 kilometres to the south. The Chehalis River enters the Harrison River in a broad fan of meandering channels and mudflats. Sedge marshes cover much of the open habitat at the mouth of the Chehalis River, while the Harrison River is bordered by linear stands of large Black Cottonwood, Western Redcedar and Douglas-fir. The site is within the lower Fraser Valley, a broad floodplain (~15 km wide) bordered on the north by the granitic Coast Mountains and on the south by the Cascade Mountains. Coho and Chum Salmon have a winter spawning run here.
Significant Species - Chehalis River Estuary was designated an IBA for globally significant numbers of Bald Eagle and Trumpeter Swan.

The area attracts large numbers of Bald Eagles from October through January, which feed on spawning Coho and Chum Salmon. Between 1000-5000 eagles are regularly seen in the IBA during that time. The eagle concentration is perhaps the third largest in the world after the Chilkat River, Alaska; and Squamish River, British Columbia.

The annual Fraser Valley Bald Eagle count on the third weekend of November incorporates six locations from the western shore of Harrison Bay to where the Morris Valley Rd meets the water. The highest counts of eagles are found along the Harrison at the confluence of the Chehalis River -- a few hundred meters east of the Chehalis Flats and only visible from a boat. The eagle numbers build through November, peak in December and wane through January and February. On December 18, 2010 , in a three kilometer stretch along the Harrison River , 7362 bald eagles were counted.

Trumpeter Swans are present in winter in the area in significant numbers. On the 2014 Christmas Bird Count, 1461 were recorded. The swans congregate on Harrison Bay after feeding in area fields, though for the past several years they have been scarce in the estuary itself. Numbers of Tundra Swans are increasing.

Other Species of Conservation Interest - The IBA supports several species determined to be Threatened or Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC; wildlife species that have been assessed as at risk by COSEWIC may qualify for legal protection and recovery under Canada's Species at Risk Act).

  1. Great Blue Heron (fannini subspecies) (Special Concern, COSEWIC) occurs in the IBA.
  2. Peregrine Falcon (Special Concern, COSEWIC) hunts within the IBA and winters regularly there.
  3. A small colony of western Purple Martin (subis/arboricola subspecies) (Special Concern, COSEWIC) have nested in the IBA since 2014, the most eastern successful colony in BC.
  4. Wood Duck, Pied-billed Grebe, Osprey, Red-tailed Hawk, Black-headed Grosbeak, Bullock's Oriole, and Grey Catbirds nest in the IBA.

IBA Criteria
SpeciesT | A | I Links Date Season Number G C N
Bald Eagle 2010 - 2018 FA 2,725 - 4,000
Bald Eagle 2010 WI 7,362
Trumpeter Swan 2008 - 2009 FA 292 - 509
Trumpeter Swan 1997 WI 413
Note: species shown in bold indicate that the maximum number exceeds at least one of the IBA thresholds (sub-regional, regional or global). The site may still not qualify for that level of IBA if the maximum number reflects an exceptional or historical occurrence.
Conservation Issues
Eagle concentrations are highly dependent on salmon populations, which have been generally declining on the Pacific Coast due to over-harvesting, habitat degradation of spawning areas, and other factors. Eagle movements up and down the coast and the huge gatherings of eagles on the Chehalis Flats are related to weather conditions up north and salmon availability for the eagles throughout the area. Normally the wintering eagles are dispersed all along the northwest coastal salmon rivers, feasting on the carcasses until they are eaten out or frozen under the ice. As this food source is depleted the eagles move south. There has been a gradual increase in numbers of wintering eagles at Harrison Mills over 15 years which coincides with a decline in other spawning salmon populations in northern rivers. The flats are the southern-most of the large salmon spawning areas and offer a feasting area for the wintering eagles where they build up reserves for winter, before again heading north for breeding.

This area is easily accessible along Highway 7, and the concentration of eagles is an important wildlife viewing opportunity for residents of the Lower Mainland, including Vancouver. Increased visitors spreading beyond the official bird viewing sites are a disturbance concern. Kayaking and walking through the flats is a disruption to the eagles.

Tree-cutting for housing developments reduces the number of large, mature trees available for eagle roosting. Air traffic flying low over the estuary disturbs the birds, and private planes even occasionally land on the estuary flats. Model planes and drones are a new issue. Off leash dogs continue to be a problem. Logging and gravel extraction has occurred north of the estuary.

The Fraser Valley Bald Eagle Festival, an annual event held since 1996, carries out Bald Eagle counts on each day of the two-day event in November. Community groups promoted the the 'Chehalis Flats Bald Eagle & Salmon Preserve' to reduce disturbance on the flats from October through February.

In 2010 the Pacific Fisheries Resource Conservation Council (PFRCC) designated the Harrison River as the first Salmon Stronghold in Canada under the North American Salmon Stronghold Partnership. Partners include the Rivers Institute at BCIT, the Chehalis First Nation, the Nature Trust, and the Portland, Oregon-based Wild Salmon Center. The Salmon Stronghold designation serves as a rallying point for local residents and diverse interests to work together to protect the uniqueness of the river’s salmon values while supporting sustainable development.

In November 2016, the Provincial Government established the Lhá:lt / Harrison-Chehalis Wildlife Management Area (WMA), which encompasses more than 31% of the IBA. Located in the heart of the Sts’ailes First Nation’s traditional territory, the Lhá:lt / Harrison-Chehalis WMA covers over 1,000 hectares of highly productive, seasonally flooded wetlands at the confluence of the Chehalis and Harrison rivers north of Chilliwack near Harrison Mills.

The WMA includes 201 hectares of private conservation lands held by The Nature Trust of British Columbia. These conservation lands are leased to the Province. Ducks Unlimited Canada shares title to a small wetland that is also part of these holdings.

The IBA Program is an international conservation initiative coordinated by BirdLife International. The Canadian co-partners for the IBA Program are Birds Canada and Nature Canada.
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