California Code, Government Code - GOV § 51086

(a) From and after the time when an open-space easement has been accepted or approved by the county or city and its acceptance or approval endorsed thereon, no building permit may be issued for any structure which would violate the easement and the county or city shall seek by appropriate proceedings an injunction against any threatened construction or other development or activity on the land which would violate the easement and shall seek a mandatory injunction requiring the removal of any structure erected in violation of the easement.

In the event the county or city fails to seek an injunction against any threatened construction or other development or activity on the land which would violate the easement or to seek a mandatory injunction requiring the removal of any structure erected in violation of the easement, or if the county or city should construct any structure or development or conduct or permit any activity in violation of the easement, the owner of any property within the county or city, or any resident thereof, may, by appropriate proceedings, seek such an injunction.

(b) In the case of an open-space easement granted to a nonprofit organization pursuant to this chapter, such organization shall seek, through its official representatives, an injunction against any threatened construction or other development or activity on the land which would violate the easement and shall seek a mandatory injunction requiring the removal of any structure erected in violation of the easement.

(c) The court may award to a plaintiff or defendant who prevails in an action authorized by this section his or her costs of litigation, including reasonable attorney's fees.

(d) Nothing in this chapter shall limit the power of the state, or any department or agency thereof, or any county, city, school district, or any other local public district, agency or entity, or any other person authorized by law, to acquire land subject to an open-space easement by eminent domain.