Del Mar Mesa Preserve is a City of San Diego resource-based park, created over twenty-five years through the combined efforts of US Fish and Wildlife, CA Fish and Wildlife, San Diego County, the City of San Diego, environmental groups both large and small, individual developers, property owners who dedicated up to 75% of the land in exchange for density, and hundreds of citizen volunteers, including among many others, Endangered Habitats League, Center for Biological Diversity, Sierra Club, Del Mar Mesa and Carmel Valley Planning Boards and Friends of Los Penasquitos Canyon. The route for SR56 was planned to avoid the future preserve.