Spanish explorer Gaspar de Portola founded LA's first official settlement in 1769.
That year, Franciscan missionary Juan Crespí wrote that the explorers "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," referring to the headwaters of Ballona Creek.
The Southern California Coastal Water Research Project focuses on the years between 1850 and 1890, before European settlement completely transformed the land.
In the late 19th century, the Ballona Creek's wetlands stretched over 8,100 acres, according to the researchers.
The area featured freshwater ponds, beaches, dunes, salt and tidal flats, marshes, meadows, and willow thickets (a type of plant that forms along sandbars). These served as habitats for a diverse set of flora and fauna, including migratory birds.
One of the largest wetland areas was La Cienega, a complex of ponds, meadows, pools, and marshes that stretched from Mid-City LA to South LA.
It connected to the region's other major wetland complex, Ballona Lagoon.
California became the 30th state in the Union in 1850. Los Angeles then began to grade its streets.
Over time, many of these wetlands were destroyed by development or paved over to create a network of underground storm drains.
At the turn of the 20th century, the Ballona Lagoon wetlands were converted into Marina Del Rey, an unincorporated seaside community in LA County. Here's a photo of what it looked like before.
Today, just 1,228 acres of wetlands in the Ballona Creek watershed are left in LA.
The 130-square-mile swath of land is now home to more than 1.2 million people and includes much of western LA, Beverly Hills, Inglewood, South LA, and the Baldwin Hills.
