A HOLOCENE ENVIRONMENTAL HISTORY OF LAKE LOUISE, LAKEWOOD, WASHINGTON

Lake sediments can be highly variable in terms of their chemical and organic composition. These variations record changes in the surrounding environment, including what vegetation has grown, what the land was used for and what type of climate was present. This project is building on existing research completed on a 6-meter-long sediment core taken from Lake Louise in Lakewood, Washington. These previous studies show that a ~14,000-year history is preserved, with age control provided by radiocarbon dates, and an ash layer at 2.5 meters depth that has been chemically fingerprinted as the 7700 BP eruption of Mt. Mazama (Datt, 2012). The focus of the current research is on using stable isotope and diatom analysis to investigate both recent (post ~1850) and long term changes in water chemistry and productivity.

The results will be compared with existing data for Lake Louise and with other lakes nearby to further the understanding of the recent history of the Puget Lowlands. Preliminary gathering of stable isotope data and C/N ratios both suggest that the lake has become more organically productive. I am currently examining the diatom assemblage, which will provide more insight into the historical productivity of the lake, as well as indicate historical acidity and temperature range variations.