California Code, Civil Code - CIV § 816.54

(a) A greenway easement is an interest in real property voluntarily created and freely transferable in whole or in part for the purposes stated in subdivision (c) of Section 816.52 by any lawful method for the transfer of interests in real property in this state.

(b) A greenway easement shall be perpetual in duration.

(c) Notwithstanding the fact that it may be negative in character, a greenway easement is not personal in nature and shall constitute an interest in real property.

(d) The particular characteristics of a greenway easement shall be those granted or specified in the instrument creating or transferring the easement.