PALEOHYDROGRAPHIC RECONSTRUCTIONS NEAR THE PEACE-ATHABASCA DELTA IN THE MACKENZIE RIVER BASIN OF WESTERN CANADA

Water is essential to sustain the internationally recognized ecosystem of the Peace-Athabasca Delta (PAD). Unfortunately, the limited availability of hydrometric records has made it difficult to resolve the potential effects of human activities, including flow regulation for hydroelectric production and water extraction for irrigation and oil sands processing, from natural streamflow patterns and trends. Information about past conditions preserved in lake sediments from the PAD and nearby Bustard Island in western Lake Athabasca has been used to reconstruct natural variability prior to major human influence to contextualize present conditions and predict future realistic scenarios. Paleolimnological investigations since AD 2000 have integrated radiometric, physical, geochemical, and biological data to reconstruct past changes in hydroecological conditions over decadal to multi-centennial time-scales. Among other findings, this research culminated in a 5200-year, geochemically-derived paleohydrograph for Lake Athabasca highlighting that modern society in western Canada developed during a rare interval of relatively abundant freshwater supply. Here we present a new paleohydrographic reconstruction from analysis of beach ridges in the William River Delta on the southern shore of Lake Athabasca that further supplements our understanding of changing lake level, glacial isostatic adjustment, and evolution of the PAD, knowledge that is crucial for guiding future research and informed stewardship of this dynamic and complex landscape.