Lake Whatcom Risk Assessment Project
Lake Whatcom Risk Assessment Project Summary
Lake Whatcom, in Whatcom County WA, is a multiple-use, multi-jurisdictional watershed that serves as the only drinking water source for approximately 85,000 people, while also supporting diverse fish and wildlife species. Because it has a risk for impairment, a screening level integrated ecological and human health risk assessment was conducted using the Relative Risk Method (RRM). This is the first study utilizing the RRM to create an integrated risk model framework by incorporating human health into an ecological risk assessment. The integration of human health and ecological risk assessment is critical for this study area because humans live near the lake and drink the water. As with any multiple use source water area, diverse stakeholder groups support a range of values which lead to complex and somewhat conflicted land use policies. This integrated ecological and human health risk assessment quantified the relative risks to the endpoints of birds, fish, flood control, humans, and water quality. Sources included dams, industrial discharges, land disturbance, recreation, septic and sewer systems, and transportation. Stressors included chemical, microbial, and physical contaminants released from the sources. Results showed that the sources of land disturbance, transportation, and recreation contributed the most risk to the study area. The stressor with the highest risk is phosphorus. The ecological endpoint at the highest risk is water quality, followed closely by fish and birds. The human health risk regions at the highest risk are the direct draw region and the human contact region, due to exposure to the raw water. When risk scores were integrated for ecological and human health, Risk Region 6 and Risk Region 2 had the highest total risk scores. Sources having high uncertainty and sensitivity were recreation and land disturbance. The results of this integrated human health and ecological risk assessment model can provide guidance to managers to reduce risks to both the environment and human health. Future studies would include an integrated risk assessment on the urban creeks draining to Bellingham Bay and the Nooksack River, which also drains to Bellingham Bay.
The executive summary and the thesis of Christina Maginnis are now available as downloads.