This report provides a summary of flow and lake level information for water bodies in the Peace, Athabasca and Slave river basins to provide a hydrologic background far many of the other reports published by the Northern River Basins Study. The trends in river flows for both the main stems and significant tributaries, and for lake levels, for both natural and regulated conditions were examined. Ice processes were discussed along with some of the environmental effects. Regulation on the Peace River has altered the hydrologic regime of both the Peace and Slave Rivers, as well as the ice regime on the Peace River as far downstream as Fort Vermilion. Lake Athabasca and Great Slave Lake levels have also been affected by the changes in the Peace River
flow regime.