The 2015 State of the Bay Report is a science-based comprehensive assessment of the Bay’s environmental condition. The Santa Monica Bay National Estuary Program (SMBNEP) periodically conducts and makes a report on this assessment, with the goal of measuring progress in restoring the Bay’s natural habitats and resources, educating the public about the Bay’s valuable natural resources, and identifying and helping scientists and managers to address remaining and emerging challenges. More specifically, this report provides information that can be used both to gauge the progress in implementing the Bay Restoration Plan (BRP) and to guide updates of the BRP to meet new and existing challenges.