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Lower St. John River (Sheffield / Jemseg) (NB010)


Lower St. John River (Sheffield / Jemseg) (NB010)

Oromocto, New Brunswick

Latitude 45.803°N
Longitude 66.257°W
Altitude 8 - 15m
Area 751.29km²

Site Description

The Lower Saint John River site, located in south-central New Brunswick, extends 25 km along the St. John River, from 5 km northeast of the town of Oromocto to 25 km east of Oromocto. The site includes the Portobello National Wildlife Area, Gilbert Island, French Lake, Big Timber Lake, Grand Lake Meadows, and the southern edge of Grand Lake. The area is under tidal influence (tidal influence extends upstream to Mactaquac dam); extensive spring flooding have resulted in the creation of a unique hardwood and flora complex creating the single largest wetland complex in Atlantic Canada. Habitats here include marshy islands, backwaters, creeks and marshes that extend 2 to 5 km beyond the main riverbanks.


With its extensive marshes and backwaters, the Lower Saint John river provides breeding habitat for the nationally vulnerable Yellow Rail. Due to the rails secretive nature, and the inaccessibility of much of the site, their precise numbers are not known. However, it is estimated that the population contains at least 100 birds, which is over 1% of their North American population.

In 1937, the Black Terns found at Big Timber Lake were the first of the species found breeding in Canada east of Ontario. The area is still the largest breeding concentration in the northeast, with perhaps over 100 birds being present. These numbers are nationally significant, since they probably are equal to 1% of the Canadian population (which has not been determined with any certainty).

The region supports Atlantic Canadas only breeding population of Greater Scaup. Thousands of waterfowl use this site during migration. Although total numbers of staging species may occasionally approach 10,000 (nationally significant), complete data for this large and complex area are lacking.

Conservation Issues

A major divided highway has been constructed through these marshes posing a threat to their integrity. The area has been a focal point for the development of large (>100ha) commercial cranberry production facilities, which have removed local forests and changed seasonal flooding and water drainage patterns. Other local land uses, such as tree cutting, and recreational development, which is associated with the proximity to the provincial capital and other urban centres, are also concerns.

Much land along the river is privately owned, while some is provincial crown land. Land assembly for Portobello National Wildlife Area (>4000 ha) began in the 1970s and is presently two-thirds completed. In addition, Grand Lake Meadows (~3200 ha) and adjacent wetlands (>1500 ha) are currently owned and managed by the province and the partners of the Eastern Joint Venture. It has also been proposed as a protected area under the New Brunswick Protected Areas Strategy. Many waterbird surveys and several thesis studies have been completed or are underway within the site.

IBA Criteria Habitats Land Uses Potential or Ongoing Threats Conservation Status
Yellow Rail
Number Year Season