The IRWD San Joaquin Marsh Wildlife Sanctuary, a wetland of distinction, is a place for everyone to enjoy the beauty of nature. Visitors can walk along the trails, watch the more than 200 bird species that visit the marsh, take photographs, or simply relax under a native willow and listen to the sounds of nature. Because the Marsh is a wildlife sanctuary and place for quiet reflection, vehicles, bicycles, drones, dogs, horses, and other animals are not permitted.

The wetlands are a critical component of IRWD's Natural Treatment System. They naturally clean urban runoff from San Diego Creek and help to protect the environmentally sensitive Upper Newport Bay. After interacting with the bulrush and other plants for two to four weeks, up to 75% of the nitrogen is removed. The cleaner water is returned to the creek to continue its journey to Upper Newport Bay and the ocean.

The Marsh is full of educational opportunities, serving as a living laboratory for students, teachers and the public. In cooperation with Discovery Cube Orange County and the local chapter of the National Audubon Society, people can enjoy a variety of wildlife educational programs and tours, including an active school field trip program.