Quartermaster Harbor Nitrogen Management Study

This study will evaluate the role of nitrogen in the risk of exceeding a critical threshold during low-level dissolved oxygen events in Quartermaster Harbor, a sensitive marine embayment of Vashon-Maury Island in Puget Sound. Sources of nitrogen will be identified and quantified, and nitrogen impacts on dissolved oxygen in Quartermaster Harbor will be modeled.

The expected outcomes of this study are recommendations for policy changes in the 2012 King County Comprehensive Plan update for nitrogen management on Vashon-Maury Island. The policy recommendations will be transferable to similar rural areas in Puget Sound where inputs of nutrients from small streams, On-Site Septic systems and direct ground-water discharge flow are impacting the receiving waters.

The Quartermaster Harbor Nitrogen Management Study will be conducted in three phases starting 2009 through 2012.

• Phase 1 will estimate the nitrogen loadings from various potential sources using existing data and published literature values and by preliminary water quality sampling of streams, groundwater and marine waters.
• Phase 2 will build upon the results of Phase 1 by continuing to collect data, modeling the contributing nitrogen loadings in to Quartermaster Harbor, and develop receiving water models of Quartermaster Harbor.
• Phase 3 will link the nitrogen loadings to Quartermaster Harbor dissolved oxygen levels and by simulating the effects of nitrogen management scenarios on Quartermaster Harbor. New policy recommendations for nitrogen management on Vashon-Maury Island will be developed working with stakeholders.

Project Info

Dissolved oxygen levels in Quartermaster Harbor have been recorded near lethal levels over the last three years of monthly monitoring by King County. As a poorly flushed embayment of Puget Sound, Quartermaster Harbor has many characteristics similar to Hood Canal, which has experienced multiple, lethal, low-oxygen events. Similarities with Hood Canal include increased upland development and nitrogen loading, high value shellfish fisheries, and high value ecological habitat.

Model Output from EDFC Phase I South Puget Sound Study (S. Albertson)

Sources of nitrogen will be identified and quantified, and nitrogen impacts on dissolved oxygen in Quartermaster Harbor will be modeled. To inform future actions, the degree of improvement in Quartermaster Harbor dissolved oxygen will be modeled for various nitrogen management strategies and compared to conceptual costs of each strategy. The Project Objectives are as follows:

• Determine nitrogen loadings to Quartermaster Harbor by source type: On-Site Septic systems, livestock (manure), fertilizer, alder forests, and other. Loading from On-Site Septic will be further broken down by age (new and those older than 20 years), and by technology (basic or alternatives that remove nitrate). Collect high frequency marine data in Quartermaster Harbor.
• Model the loadings with a surface-subsurface hydrologic model to simulate the time varying loads to a receiving water (marine) model. A stable isotope study will provide data on the source distribution to Quartermaster Harbor. The models will be calibrated to data collected from this study.
• Identify Best Management Practices that address the land uses with the largest nitrogen loadings with assistance from regulatory and policy partners.
• Model the effectiveness of nitrogen management Best Management Practices on Quartermaster Harbor dissolved oxygen levels, and compare the level of effectiveness of different management options with conceptual cost estimates.
• Develop new policies related to nitrogen management on Vashon-Maury Island and recommend management actions for implementing the new policies in the 2012 King County Comprehensive Plan update.

Project partners:

Project Data, Documents and Maps

Surface, ground and marine water data are being collected as part of this project. The project will have numerous publications during the study timeline. The data, documents and maps can be found in the documents section. EPA approved the Quality Assurance Project Plan in June 2009.

Public Involvement

This project works closely with the Vashon-Maury Island Groundwater Protection Committee to broaden the understanding of the impacts to Quartermaster Harbor.

» Project News is an e-mail list about project information.

Care to join us?

Groundwater Protection Committee meetings are open to the public and held quarterly on the 4th Wednesday of the month (Jan/Apr/Jul/Oct).

This page is produced by the King County Groundwater Protection Program. To learn more about this group and its responsibilities, please read about the Groundwater Protection Program.