A watershed is a sloping basin through which a river flows and drains into another, larger body of water. La Ballona Watershed includes parts of Los Angeles, West Hollywood, Beverly Hills, Culver City, Inglewood and Marina del Rey. The watershed is drained by a series of rivers, creeks, channels and washes which carry water to the main river system, La Ballona Creek and then to Santa Monica Bay.

Today's concrete-lined Ballona Creek was once a natural river, La Ballona. The river helped support the Gabrielinos, native people who lived along the high banks of the river and within the surrounding wetland. The watershed was a great basin filled with forests and grasslands with deer and rabbit, berries, acorns, grasses and seeds. Rivers flowing through the basin created lakes, ponds and marshlands. The Gabrielinos called the land pwinukipar, which means "it is full of water."

La Ballona Creek met the ocean at the Ballona Wetlands, creating an estuarine wetland habitat. An estuary was formed where the freshwater current at the mouth of the creek met the ocean's salty tide. In the dry season, the marine influence from the Pacific Ocean brought waves of salt water into the wetland, while during the rainy season, the wetland overflowed with rainwater, flushing out the saltwater.

Similar to what your heart does for your body, an estuarine wetland pulses blood in the form of enriched water. The nourishing environment is filled with birds, including the endangered Belding's Savannah Sparrow. Rare Burrowing Owls nest in the bluffs along the creek while Great Blue Herons and egrets fish in the shallow waters and mudflats alternately flooded and left bare by rains. Native Redtailed Hawks and non-native Red Foxes are predators that hunt for small mammals like the Salt Marsh Shrew and House Mouse. The wetland also serves as a nursery for many species of fish. Growing within the wetland are native and non-native plants. Pickleweed is a native plant that provides crucial habitat for the Belding's Savannah Sparrow. Other native plant species include marsh heather, salt grass and cattails. Non-native or "introduced" plants and animals threaten the wetland community. Non-native plants in the wetland include ice plant and poisonous castorbean.

Ballona Creek today is a paved channel designed to carry stormwater straight to the ocean. Cutting off freshwater and tidal influences, the channel is effectively drying out most of the Ballona Wetlands. Although many plants and animals still live in the wetland, they are only a fraction of what the creek and wetland could support in their natural state. In addition, polluted water shuffled straight into the Bay is more harmful that it would be if it were allowed to percolate or filter normally through the wetland. Stormwater or urban runoff contains everything that is left on the street, swept into a catch basin or poured into the gutter. Toxins like motor oil, antifreeze, pet droppings, pesticides, yard clippings and litter all run off into the largest storm drain flowing into Santa Monica Bay - Ballona Creek. Plans are underway to help stop pollution to Ballona Creek and to the Ballona Wetlands. Every person does their part to create this problem - and every person in the area is needed to help solve it and return at least part of La Ballona to the rich and abundant natural resource that it once was.