This wonderful nonprofit organization is doing some great trail related work, which you can read about on their website.
An excerpt.
“Local residents living in the vicinity of the Central California Traction Company (CCTC) Rail Corridor founded the Central Valley Rails to Trails Foundation (CVRTF) in the year 2000. CVRTF is a non-profit public charity that leads a coalition of recreation and community organizations, businesses and local residents who are committed to the goal of utilizing the CCTC corridor for non-motorized recreation and alternative commuting. The Foundation has a 501(c)(3) tax-exempt status and benefits from the services of its all-volunteer Board of Directors.
“The proposed trail will provide a safe location for hiking, biking, and equestrian travel, and will provide access to numerous planned and existing trails and parks in both Sacramento and San Joaquin Counties. Visit the Map Page to view the planned route and proposed trail design.”