Reduced River and Lake Ice

Ice cover reduction in the southern Mackenzie Basin is resulting in profound changes in wetlands in areas such as the Peace-Athabaska Delta. The Delta contains numerous isolated lakes and wetlands, called perched basins, that are normally replenished every several years when ice jams during spring melt cause wide scale flooding.

The flooding refills the basins even though they have no direct connection with local rivers or ground water. Because warmer rivers have reduced the thickness of ice cover, ice jams are no longer as substantial and many perched basins have shrunk or dried up completely. [13]