The National Park Service Inventory and Monitoring (I&M) Program measures long-term changes in the condition of natural resources throughout the National Park System. As part of this effort, the San Francisco Bay Area Network (SFAN), which encompasses Eugene O'Neil National Historic Site, Fort Point National Historic Site, Golden Gate National Recreation Area, John Muir National Historic Site, Muir Woods National Monument, Pinnacles National Monument, Point Reyes National Seashore, and the Presidio of San Francisco, has developed a detailed water quality monitoring plan.