Cal. Gov. Code § 54233
If the local agency does not agree to price and terms with an entity to which notice of availability of land was given pursuant to this article, or if no entity to which a notice of availability was given pursuant to this article responds to that notice, and 10 or more residential units are developed on the property, not less than 15 percent of the total number of residential units developed on the parcels shall be sold or rented at affordable housing cost, as defined in Section 50052.5 of the Health and Safety Code, or affordable rent, as defined in Section 50053 of the Health and Safety Code, to lower income households, as defined in Section 50079.5 of the Health and Safety Code. Rental units shall remain affordable to, and occupied by, lower income households for a period of at least 55 years for rental housing and 45 years for ownership housing. The initial occupants of all ownership units shall be lower income households, and the units shall be subject to an equity sharing agreement consistent with the provisions of paragraph (2) of subdivision (c) of Section 65915. These requirements shall be contained in a covenant or restriction recorded against the surplus land prior to land use entitlement of the project, and the covenant or restriction shall run with the land and shall be enforceable, against any owner who violates a covenant or restriction and each successor in interest who continues the violation, by any of the entities described in subdivisions (a) to (f), inclusive, of Section 54222.5. A local agency shall provide a copy of any restrictions recorded against the property to the Department of Housing and Community Development on a form prescribed by the department.
Ca. Gov. Code § 54233