Here are some links that we've found useful while researching California grasslands and their management:
California Land Use Planning Information Network - links to information about planning in every California county.
California State Association of Counties - links to every California county website.
CERES:The Catalogue of Conservation Banks in California
Division of Land Resource Protection: Williamson Act Program - information and limited spatial data on Williamson Act holdings throughout California.
Division of Land Resource Protection: Williamson Act Status Report 2004