Today, Ballona Lagoon is a (16-acre) remnant of a formerly extensive coastal wetland. Like other southern California wetlands, urbanization has reduced its size and degraded its habitat over the last century. Historically, Ballona was much larger (2,200 acres), and formed over a much longer period (18,000
As the last glacial period ended, rising sea levels inundated the mouth of Ballona Creek to create Ballona Bay along the base of Del Rey Bluffs. Over time, sand spits eventually closed-off the outer bay to create a lagoon, while creek sediments filled the inner bay. Extensive salt and fresh-water marshlands developed.
The earliest settlers arrived about 7,000 years ago. The Tongva people lived in scattered campsites along the bluff tops. From 3,000 to 1,000 years ago, settlements were established below the bluffs, initially along Ballona Creek, and then at Ballona Lagoon.
In the early 1900's, Abbot Kinney constructed the Venice Canals, and tapped into Ballona Lagoon as a water source. Oil was discovered in the late 1920's. Production peaked during the 1930's, but persisted until the 1970's. As oil reserves decreased, residential and other development increased. Ballona Creek's channelization (1930's), and Marina Del Rey's construction (1960's), permanently split Ballona Lagoon from
its twin (named, "Del Rey Lagoon") to the south.
In recent years, community concern about Ballona Lagoon's deterioration led to the establishment of Ballona Lagoon Marine Preserve in 1988. Community intervention halted a proposed marina in 1997. The east bank was restored in 1999, while the west bank will be restored by 2012.