Every weekday while commuting to Downtown Los Angeles from Long Beach on the Metro Blue Line train, I pass over both the Los Angeles River and Compton Creek. The section of river and tributary I pass over is located north of the 405 freeway, near the 710 freeway. Here, the Los Angeles River is represented as a concrete lined channel, while the Compton Creek maintains a natural soft-bottom. For several months I’ve watched the dramatic evolution of these two river channel habitats, being witness to the devastation of one and the seemingly miraculous emergence of another.
Sometime this summer a photosynthetic ecosystem emerged on the surface of the concrete lined channel. From what I can ascertain, algae grew on the concrete surface, growth fed by nutrients available in the thin film of water that spread across the concrete floor as it overflowed over the low flow channel. Birds, such as killdeer, ducks and black-necked stilts, then began feeding on the aquatic invertebrates that collected in the pockets of algae growth. More recently, a thin layer of sediment has been trapped by this algae growth, forming small islands of flowering plants living within the isolated channel. These islands appear quite verdant and beautiful from the train, like miniature vignettes of an island ecology.
By contrast, the soft-bottomed portion of Compton Creek supports a thickly vegetated growth of rushes and exotic plant species – at least until about two weeks ago, when the vegetation was removed (alongside the nests, protective cover, and food sources) by the Los Angeles County Flood Control District in anticipation of winter rains. The soft-bottomed portion of Compton Creek is considered a remnant wetland habitat, and supports many wildlife species including egrets and herons. Vegetation management is currently necessary to prevent flooding and is authorized by the US Army Corps of Engineers in order to maintain channel flood capacity. But, vegetation management is necessary because the channels and levees were designed without vegetation incorporated into volume calculations.
Being witness to the Compton Creek habitat wiped out (albeit it overrun with exotic species) and anticipating a similar scouring of the miniature islands within the channel of the L.A. River makes we wonder: How can we have both flood protection and space for habitat?