Elkhorn Slough Reserve, California

Cultural History

The first Native Americans migrated into the Monterey Bay area between 10,000 B.C. and 6,000 B.C. There is some evidence of native presence around the slough as early as 6000 years ago. Thousands of years before Spanish and Mexican settlers arrived, Ohlone Indian villages thrived in the slough's mild environment. Indian middens around the slough are full of the shells of marine invertebrates and the bones of birds and mammals.

The Spanish brought cattle whose grazing habits, along with seeds in fodder brought from Europe, had a tremendous impact on the habitat. Many of the nonnative plants present today became established at this time, displacing native species and completely changing the landscape.

American settlers moving into California farmed the slough's fertile, coastal valley during the 1800's, beginning what is known as the Reclamation period. They built a system of dikes to drain additional land for crops and dairy pastures. Chinese immigrants were also among the first to dike, ditch and drain the local wetlands for agricultural use. Wheat, sugar beets, potatoes and other products were shipped by schooner to gold-boom San Francisco from the small port of Moss Landing established at the mouth of the slough. By the 1870's the hefty coastal schooners were replaced by a railroad built along the edge of the estuary. More dikes and evaporation ponds were created at the slough's mouth to concentrate and extract precious salt. While the largest area of wetland habitat was reclaimed before 1900, additional significant wetland areas were reclaimed in the 1930's and 1940's.

The construction of Moss Landing Harbor was completed in 1947. The opening of the harbor was the most significant known impact on the hydrology and wildlife of Elkhorn Slough. Prior to the construction of the harbor, tidal action in the slough was very restricted, the slough existing as a shallow, quiet-water embayment. The new jetty at the harbor mouth now causes the slough to drain quickly, exposing shallow flats of eel grass at low tide, which had formerly been underwater at all stages of the tidal cycle. The increase in tidal flow has contributed to significant erosion of the main channel and bordering mud flats.

Recognizing the pressing need to protect the slough from further development, the California Department of Fish and Game purchased 1,000 acres in 1980, calling it Elkhorn Slough Ecological Reserve. Because of the slough's critical location and resources, the Reserve became the 6th estuarine area to become part of the National Estuarine Research Reserve System in 1979. In 1983, dikes used to drain the land were broken and, once again, tidal waters flowed deep into the marsh. By 1985, reserve lands increased to 1,330 acres. The 400 cows that once resided there have been replaced by hundreds of resident and migratory wildlife species.