Approaches to Identify Exceedances of Water Quality Thresholds Associated with Ocean Conditions.

摘要

Estuaries along the west coast of the United States periodically have high nutrient, high chlorophyll a, and low dissolved oxygen levels due to the intrusion of oceanic water into the estuaries. This oceanic water often has water quality conditions which exceed water quality standards and indicators of eutrophication status. Tools are needed to distinguish such exceedances of water quality thresholds related to import of oceanic water from other causes. In this report, we present an application of logistic regression models to predict the probability of exceedance of water quality thresholds using floodtide nutrient and dissolved oxygen data from the Yaquina Estuary. Models including water temperature and salinity correctly classified exceedances of dissolved inorganic nitrogen and phosphorous thresholds about 90% of the time, and for dissolved oxygen about 80% of the time. Inclusion of in situ fluorescence in the logistic regression model for dissolved oxygen improved the model performance and reduced the rate of false positives.