PT03 Landscape-Scale Ecological Risk Assessment
Exhibit Hall
8:00 AM - Tuesday, 11 November 2003
(PT047) Ecological risk assessment for chinook salmon in a rapidly-urbanizing watershed.
Washburn, B1, Heinzel, A1, Donald, J1, Ayres, E2, Knapp, E2, Lieberman, S2, Love, J2, Vodopals, K2, 1 Office of Environmental Healtlh Hazard Assessment, Sacramento, CA, USA2 Bren School of Environmental Science and Management, UCSB, Santa Barbara, CA, UDA
ABSTRACT- Secret Ravine Creek is a 2nd order stream in western Placer County, 20 miles east of Sacramento, California. This region is the fastest growing area of the state, placing significant pressure on the declining populations of salmonids. An ecological risk assessment, based on the relative risk model (RRM), was performed to rank chemical, physical, and biological stressors and serve as a guide for restoration/mitigation efforts. This model ranks sources of stressors, exposure, and the effects of stressors relative to each other. Small modifications were made to the original model, a key one being the use of stressor-response relationships as part of the effects filter. Preliminary analysis suggests that fine sediments, contaminants in the sediment, habitat alterations, and flow are important stressors whereas invasive species and high water temperature were ranked low. Key sources of these stressors were landscaped areas, impervious surfaces, legacy effects of mining, and dirt roads. The major strength of the RRM is the ability to integrate disparate types of data into a single watershed assessment. A weakness is that different stressors are assigned the same relative ranking, although some might have a greater impacts on the assessment endpoint than others. Final analysis of the data and the strengths and weaknesses of the model will be presented at the meeting.
Key words: risk, ERA, salmon, stressors