Ballona Wetlands Ecological Reserve is a protected area that once served as the natural estuary for neighboring Ballona Creek. The 577-acre (2.34 km2) site is located in Los Angeles County, California, just south of Marina del Rey. Ballona—the second-largest open space within the city limits of Los Angeles, behind Griffith Park—is owned by the state of California and managed by the California Department of Fish and Wildlife. The preserve is bisected generally east-west by the Ballona Creek channel and bordered by the 90 Marina freeway to the east.

Ballona Creek is an 8.5-mile (13.7 km) channelized stream in southwestern Los Angeles County, California, United States, that was once a "year-round river lined with sycamores and willows". The urban watercourse begins in the Mid-City neighborhood of Los Angeles, flows through Culver City and Del Rey, and passes the Ballona Wetlands Ecological Preserve, the sailboat harbor Marina del Rey, and the small beachside community of Playa del Rey before draining into Santa Monica Bay. The Ballona Creek drainage basin carries water from the Santa Monica Mountains on the north, from the Baldwin Hills to the south, and as far as the Harbor Freeway (I-110) to the east.