Citation:

BROWN, C. A., W. G. NELSON, J. E. KALDY, III, P. M. ELDRIDGE, B. L. BOESE, T. H. DEWITT, H. LEE, II, J. H. POWER, AND D. R. YOUNG. An approach to developing nutrient criteria for Pacific Northwest Estuaries: A case study. Presented at Presentation for OW/ORD Seminar Series, Washington, DC, October 15, 2008.

Impact/Purpose:

This presentation provides an overview of an approach to developing nutrient criteria for Pacific Northwest (PNW) estuaries, based on a case study of Yaquina Estuary, Oregon.

Description:

This presentation provides an overview of an approach to developing nutrient criteria for Pacific Northwest (PNW) estuaries, based on a case study of Yaquina Estuary, Oregon. The approach is based on a synthesis of research from field studies, analyses of historical trends in water quality parameters, and a variety of modeling approaches. The Yaquina Estuary is strongly influenced by ocean conditions during the dry season (May-October), which is the time of biological utilization of nutrients. Such important regional drivers influence both criteria development and compliance monitoring, and need to be integrated into the criteria development process. Based on a scientific weight of evidence approach, median dry season values for most water quality parameters could be used as interim criteria. Compared to criteria that might be based on median values, the current Oregon DO criterion appears to be more conservative, while the current Oregon chlorophyll a criterion may not be sufficiently conservative to maintain current conditions. The use of existing regional datasets (e.g. EPA’s National Coastal Assessment) to extrapolate criteria to similar systems in the region is also being explored by WED. Future research directions include examination of statistical approaches to compliance monitoring which could be included in a comprehensive package of potential approaches for developing estuarine nutrient standards for the PNW.

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