Sacramento River
A Guide to Recreation and Public Access
conservation easement
Legally binding restrictions that landowners voluntarily place on their properties that bind present and future owners; these restrictions limit certain rights and uses of the property for conservation, preservation or restoration purposes.

More info:
http://ceres.ca.gov/foreststeward/html/consease.html
http://www.natlands.org/library/consease.html
http://www.landconservation.org/projects.html
http://xaosearch.com/1691686/The_Conservation_Easement_in_California.html