Even during LA’s driest months, there is a constant flow of water in our storm drain system. For example, Ballona Creek drains over 11,000 gallons per minute from 130 square miles of the Los Angeles basin. This water comes from springs, landscape irrigation overspray, car washing, and other sources. The water is polluted with tire dust, motor oil, animal feces, and trash.
Alongside the Metro E-Line tracks at the Westwood/Rancho Park station, community groups developed the Westwood Greenway. This project is an urban oasis that provides a home for nearly 500 species of indigenous plants, insects, and birds, while cleaning storm drain water. Water from a channel running below Overland Avenue is diverted into a stream running along the north side of the rail line. This water then flows into a second stream along the south side of the line, before returning cleaner into the storm drain system.
This beltway is home to plants from three distinct Southern California eco-systems: riparian, oak woodland, and coastal sage scrub. The plants and trees of these environments pre-date the arrival of Europeans, and they evolved to thrive in low-nitrogen soil with little water. In contrast, non-native plants consume six times more water and often require nitrogen fertilizer. Many indigenous plants go dormant in the summer.
Native trees in the greenway include Western Sycamore, Santa Cruz Island Ironwood, willows, and the Catalina Cherry. The native oak trees are a keystone species, supporting an entire ecosystem. Some other facts I learned include:
You may ask how contaminated storm water can support a healthy ecosystem. This water is first passed through a separator, which removes large contaminants like trash. The water then passes through a sand filter, which removes sediment. But the last stage of water cleaning is the most remarkable. The water flows through a natural bioswale, where plant life removes more contaminants. Sunlight helps to kill the bacteria in the water. The result is cleaner water returning to the storm drain system, eventually entering the Pacific Ocean.
If you missed this tour, you can visit the Westwood Greenway by exiting the the Metro E- line at the Westwood/ Rancho Park Station. Soon, a volunteer will be available 25 hours weekly to provide tours of information about this urban oasis as part of a SCWP grant. Go to https://westwoodgreenway.org or contact ellabogdanski@alumni.usc.edu for more information.