The Gardena Willows Wetland Preserve occupies 13.6 acres (55,000 m2) of land owned by the City of Gardena, in Los Angeles County, California. The preserve is the last intact remnant of the former Dominguez Slough, an important vernal marsh and riparian forest with riparian zones that once covered as much as 400 acres (1,600,000 m2) of this area, known as the South Bay region. The preserve has 9.4 acres (38,000 m2) of wetland and 4.2 acres (17,000 m2) of upland. The wetlands have a natural depression where water remains for such a significant time that plants and animals not adapted to water and saturated soils cannot survive. The upland, which remains dry outside of the rainy season, supports plants which thrive with these drier conditions. The slough is a part of the Dominguez Watershed, 96% of which is now covered with concrete and man-made structures. Located on the traditional lands of the Tongva, it is believed that these indigenous people were able to commute by canoe around much of the area. Tongva villages were located throughout much of what is now Los Angeles and Orange Counties as well as three southern Channel Islands as distant as 60 miles (97 km) from the coast of Los Angeles County.

Gardena is a city located in the South Bay region of Los Angeles County, California, United States. The population was 58,829 at the 2010 census, up from 57,746 at the 2000 census. Until 2014, the US census cited the City of Gardena as the place with the highest percentage of Japanese Americans in California. Gardena's Japanese American population contributes to the South Bay region of Los Angeles being home to the highest density of Japanese companies within the mainland United States.