Seasonal and yearly trends of fecal coliform across four different land use types in Skagit County, Washington



Journal Title

Journal ISSN

Volume Title



Fecal coliform pollution in watersheds puts human health at risk. In watersheds with mixed land use, it is hard to distinguish pollution sources. In Skagit County, Washington, elevated fecal coliform levels have led to public beach closures and shellfish harvesting closures. Different sources of fecal coliform pollution in Skagit County include agricultural runoff, mismanaged livestock and domestic waste, faulty septic systems, and stormwater runoff. Identifying specific pollution sources is difficult, but a broader analysis of fecal coliform trends in different land use areas will help guide mitigation efforts. In this paper, sampling sites were categorized into four different land use types: rural, marine, residential, and commercial. Using four long term monitoring datasets, yearly and seasonal trends were detected. Rural sites, including agricultural land, had predictable seasonal patterns with high fecal coliform in the summer and low fecal coliform in the winter. Conversely, marine areas had high fecal coliform in the winter and low fecal coliform in the summer. The seasonal trends identified in this paper can help inform future planning and strategies to reduce fecal coliform pollution in different land use areas in Skagit County, Washington



Watershed, Fecal Coliform, Pollution