Environmental effects of river ice, The Saint John (Wolastoq) River, New Brunswick, Canada

The Saint John (Wolastoq) River (SJR) is a major international river flowing through the State of Maine, USA, and the Province of New Brunswick, Canada. In terms of river length and basin area, it is one of the largest rivers on the eastern seaboard of North America south of the St. Lawrence River system. Subject to seasonal ice cover, ice conditions vary along the SJR due to natural differences in climate and terrain, and due to anthropogenetic changes, such as the construction of dams. Ice formation, growth, and breakup along the SJR affects its hydraulic and ecological regimes and leads to the potential for ice jamming that has caused severe flooding and ice runs. Ice affects river erosion, flooding, ecology, water quality, and recreational uses of the SJR. An overview of typical winter climate and ice season characteristics along the SJR from Dickey, Maine, USA to Saint John, New Brunswick, and some of its environmental consequences are summarized in this review paper. Ice processes and phenomena that occur along the SJR occur along other northern rivers, and can cause similar environmental concerns and consequences that should not be ignored in river engineering and basin management.