Publication Summary

This is the study plan for the Deschutes River continuous nitrate monitoring.

Future marine Total Maximum Daily Load (TMDL; water cleanup) studies and water quality modeling projects in Puget Sound will need accurate and highly resolved time series of nitrate discharge from fluvial sources.

For this study, a Submersible Ultraviolet Nitrate Analyzer (SUNA) will be deployed in the Deschutes River at the E. Street Bridge in Tumwater from November 1, 2009 through October 31, 2010. The Deschutes River is high in nitrate and discharges to the sensitive South Puget Sound basin.

Satlantic′s SUNA is a real-time, chemical-free sensor designed to overcome the traditional challenges associated with reagent-based nitrate analysis in aquatic environments.

The SUNA uses advanced ultraviolet (UV) absorption technology to provide accurate nitrate concentration measurements in the sometimes highly turbid, high colored dissolved organic matter (CDOM) waters of rivers, lakes, and estuaries. Data collected will be analyzed statistically to determine how nitrate concentrations (and other measured water quality parameters) behave throughout the year, with special attention being paid to patterns observed during winter storm events. This knowledge will be synthesized in the form of new or refined methods for predicting continuous daily loads of nitrate from a limited number of discrete observations.

After the stormwater fluctuation pattern of the Deschutes River is characterized, it is anticipated that the sensor will be deployed in both larger and smaller streams to provide a sense of daily nitrate variation by stream size.

Each study conducted by the Washington State Department of Ecology must have an approved Quality Assurance Project Plan. The plan describes the objectives of the study and the procedures to be followed to achieve those objectives. After completion of the study, a final report describing the study results will be posted to the Internet.

Link to EIM data for User Study ID BSAC0001