Developing a Model System for Assessing the Effects of Conversion to Sustainable Agricultural Practices in a Sensitive Estuarine Watershed, Elkhorn Slough, California
The Elkhorn Slough is located in the Central Monterey Bay area and is considered one of the most ecologically important estuarine systems in California. Over 1400 acres of the slough are in the National Estuarine Research Reserve System. Non-point source pollutants from farm use of chemical fertilizers and pesticides have been identified as a primary cause of water quality degradation in Elkhorn Slough. Erosion of sediments from cultivated slopes surrounding the slough is likewise a serious problem. In spite of this, there nave been few studies addressing the relationship between cultivation practices, inputs to the estuary, and ecological effects of these inputs.
This paper reports preliminary, first-year results of a long term project to examine the effects of agricultural production on an adjacent wetland on a 137 acre ranch in the Elkhorn Slough. In two to four years, the organizations involved in the project intend to begin converting management of the land to more sustainable agricultural practices. Portions of the land will be restored to native habitat, while others will be used for implementing and testing sustainable agricultural practices. On the upland portions of the ranch we have documented land-use history and current management practices and inputs, and we have soil characteristics, movement of sediment and runoff water, leaching of nutrients in soil water, and deposition of sediment and nutrients. In the wetlands portion we mapped out marsh vegetation, assessed macroalgae and invertebrate populations, censused birds, and measured marsh water quality. These parameters will be used in the future to assess what changes occur after conversion of the land. This information will be used as an ecological baseline for designing low-input management systems in the future. An additional goal is working with the Elkhorn Slough National Estuarine Research Reserve and the Elkhorn Slough Foundation to develop a strong partnership between the public and private sectors for addressing watershed issues in the slough.