Sources and sinks of nitrogen and phosphorus to a deep, oligotrophic lake, Lake Crescent, Olympic National Park, Washington

A significant anthropogenic source of nitrogen, particularly from diesel truck traffic on U.S. Highway 101, has been identified in the oligotrophic Lake Crescent, Olympic National Park. This finding challenges the perception of pristine water quality in this deep-water lake, renowned for its low nutrient levels. The study, conducted over 14 months, measured nitrogen and phosphorus loads from five major inflow streams, the Lyre River outlet, and multiple lake stations, while also estimating contributions from sources like leaf litter, pollen, and vehicle exhaust. Unlike other potential sources such as onsite septic systems, highway traffic emerged as a dominant contributor to nitrogen compounds in the lake's ecosystem.

Moran, P. W., Cox, S. E., Embrey, S. S., Huffman, R. L., Olsen, T. D., & Fradkin, S. C. (2012). Sources and sinks of nitrogen and phosphorus to a deep, oligotrophic lake, Lake Crescent, Olympic National Park, Washington. Scientific Investigations Report. https://doi.org/10.3133/sir20125107