| Native American Indian tribes populated San Alejo | | | | along Escondido Creek, it was a farming |
| Area 8,000 years before the first European | | | | community. Farmers plowed and planted the |
| settlers arrived. Shell middens, the refuse of | | | | riparian corridors upstream of the estuary. In that |
| hunting-gathering societies, show the earliest | | | | time those people radically changed the vegetation |
| inhabitants relied heavily on coastal resources, | | | | and terrain of San Alejo lagoon. |
| including foods such as scallops, clams, shark, | | | | The most permanent changes in San Alejo were |
| barracuda, bonito, and abalone. The ocean | | | | when the railroad was constructed, Pacific Coast |
| provided such a rich and constant source of food. | | | | Highway, and Interstate 5. Each required |
| These early settlers lived at the coast for long | | | | supporting berms that restricted water circulation |
| periods of time. More recently, so called | | | | and the natural influx of ocean water. |
| Kumeyaay occupied the San Elijo. They traveled | | | | Other negative reactions as a result of |
| seasonally to take advantage of resources both | | | | constructions were increases in sediment from |
| along the coast and inland. | | | | surface erosion and road fill failures. Fine sediment |
| In the year 1769, the Portola Expedition named | | | | can affect aquatic populations and their |
| the place San Alejo in honor of Saint Alexius. In | | | | reproduction. |
| the first years of 1800s Spaniards and settlers | | | | In the 1960s many suggestion what ot be build |
| from other parts of Europe settled the region and | | | | were made. People want to build condominiums, a |
| start to build cattle ranches. When the Gold Rush | | | | golf course, a marina, a closed saltwater lake, and |
| started more and more people came to San | | | | even a theme park with water rides. But the |
| Alejo. Their community was called Olivenhain, | | | | community replied with a big no. |