Ballona Creek is an 8.8-mile-long (14.2 km) waterway in southwestern Los Angeles County, California, whose watershed drains the Los Angeles basin, from the Santa Monica Mountains on the north, the Harbor Freeway (I-110) on the east, and the Baldwin Hills on the south. It heads in the historical Rancho Las Cienegas and flows through Culver City and the Del Rey district before emptying into Santa Monica Bay between Marina del Rey and the Playa del Rey district.
During the Pre-Columbian era, Tongva people existed as hunters and gatherers in small villages throughout the Ballona Creek watershed and other parts of the Los Angeles basin. Native American culture and land management practice was disrupted by the arrival of Spanish explorers.
In 1769, the Tongva met their first Europeans when Portola expedition came through on its way north. Continuing west after crossing the Los Angeles River, diarist Fray Juan Crespi noted that the party "came across a grove of very large alders...from which flows a stream of water...The water flowed afterwards in a deep channel towards the southwest". Researchers identified the place as the headwaters of Ballona Creek. The explorers made camp nearby on August 3.
Around 1820, a mestizo rancher named Augustine Machado began grazing his cattle on the Ballona wetlands and claimed a fourteen-thousand acre Mexican land grant that stretched from modern-day Culver City to Pico Boulevard in Santa Monica, California. Ballona Creek and Lagoon are named for the Ballona or Paseo de las Carretas land grant, dated November 27, 1839. The Machado and Talamantes families, co-grantees of the rancho, heralded from Baiona in northern Spain. After the land grant claims were lost, the area then experienced rapid growth, with open land being transformed into agricultural use.
The Ballona Creek watershed totals about 130 square miles (340 km2). Its land use consists of 64% residential, 8% commercial, 4% industrial, and 17% open space. The major tributaries to the Ballona Creek and Estuary include Centinela Creek, Sepulveda Canyon Channel and Benedict Canyon Channel; most of the creek's minor tributaries have been destroyed by development or paved over and flow into Ballona Creek as a network of underground storm drains.
At the time of Spanish settlement, the Los Angeles River turned to the west just south of present-day Bunker Hill, joining Ballona Creek just to the west of its current channel. However, during a major flood in 1825, the Los Angeles River's course changed to its present channel, and Ballona Creek became a completely distinct waterway. Much of the above-ground section of the creek was lined with concrete as part of the flood-control project undertaken by the United States Army Corps of Engineers following the Los Angeles Flood of 1938.
Ballona Creek Watershed climate can be characterized as Mediterranean with average annual rainfall of approximately 15 inches per year over most of the developed portions of the watershed. The flow rate in the Creek varies considerably from a trickle flow of about 14 cubic feet (0.40 m3) per second during dry weather to 71,400 cubic feet (2,020 m3) per second during a 50-year storm event. Ballona Wetlands and Del Rey Lagoon are connected to the Ballona Estuary through tide gates.
From northern source to southern mouth (year built in parentheses):
The historic wetland complex at the mouth of Ballona Creek probably occupied about 2000 acres. Although much of it was drained and developed, a portion remains protected. The State of California owns 600 acres of the former wetlands; the CDFW (California Department of Fish and Wildlife) owns 540 acres, and the State Lands Commission owns 60 acres, including a newly created freshwater marsh. Much of these preserved lands are designated as the Ballona Wetlands Ecological Reserve and despite historic degradation, conditions are improving. Wetland flora includes pickleweed, marsh heather, saltgrass, arrowgrass and glasswort, and a variety of upland and exotic species including brome, iceplant, oxalis, and ryegrass. Bird species of special interest observed in the reserve include nesting pairs of Belding’s Savannah sparrow (Passerculus rostratus/sandwichensis beldingi) and foraging use by California least terns (Sterna antillarum browni).
The urbanization of the watershed, and associated with it the pollution of urban runoff and stormwater, has degraded the water quality in Ballona Creek and its Estuary. Ballona Creek is listed by the Los Angeles Regional Water Quality Control Board impaired for fecal coliform, heavy metals, and pesticides. Dry weather urban runoff and storm water, both conveyed by storm drains, are the primary sources of pollutions in the Creek.
Many national, historical, archeological and cultural landmarks, tourist attractions, educational institutions, businesses and industries exist in Ballona Creek Watershed. With year-round Mediterranean climate, the area attracts immigrants and visitors from all over the world making Ballona Creek Watershed a vibrant melting pot of culture. A bike path that extends almost seven miles from National Boulevard in Culver City to the end of Ballona Creek Estuary provides opportunities for recreation in the area. Ballona Creek Estuary and Ballona Wetlands provide habitat to many species of waterfowls, shorebirds, and waders.
In the 1997 movie Volcano, Mike Roark (Tommy Lee Jones) dropped a 20-story apartment building in a controlled demolition in order to divert a flowing river of lava into Ballona Creek and thus into the Pacific Ocean.