Los Osos Back Bay is a prehistoric Chumash archaeological site in the Los Osos e coastal area in San Luis Obispo County, California, USA. These Native Americans had a significant settlement named Los Osos Back Bay on a stabilized sand dune[1] somewhat to the west of the Elfin Forest; in fact, there is another extant midden within the Elfin Forest itself.
Los Osos Back Bay is also the name for the southernmost part of the Morro Bay estuary (known by the locals as "the back bay"), where the native Chumash at the eponymous archaeological site gathered marine resources,[1] as coastal tribes along this part of the California coast regularly did.[2]