This project is aimed toward better understanding the current status and long-term trends of Chesapeake Bay in terms of its water quality standards attainment. To protect the aquatic living resources of Chesapeake Bay, the Chesapeake Bay Program partnership has developed guidance for state water quality standards, which include ambient water quality criteria to protect designated uses, and associated assessment procedures for dissolved oxygen, water clarity/underwater bay grasses, and chlorophyll-a. Insights revealed in this work are critical for understanding the dynamics of the Bay ecosystem and for further assessing the effectiveness of management initiatives aimed toward Bay restoration.