California Code, Government Code - GOV § 25365

(a) The board of supervisors may, by a four-fifths vote, grant, convey, quitclaim, assign, or otherwise transfer to the state or to any community redevelopment agency, housing authority, community development commission, surplus property authority, federal agency, city, school district, county board of education, special district, joint powers agency, or any other public agency within the county or exchange with those public agencies, any real or personal property, or interest therein belonging to the county upon the terms and conditions as are agreed upon and without complying with any other provisions of this code, if the property or interest therein to be granted and conveyed or quitclaimed is not required for county use or in the event of an exchange, the property to be acquired is required for county use.

(b) The board of supervisors may also, by a four-fifths vote, exchange real property with any person, firm, or corporation, for the purpose of removing defects in the title to real property owned by the county, or where the real property to be exchanged is not required for county use and the property to be acquired is required for county use.If the real properties to be exchanged are not of equal value, either party to the exchange may contribute cash or other real property assets, acceptable to the other party, to balance the transaction. The value of any private real property exchanged shall be equal to, or greater than, 75 percent of the value of the county property offered in exchange. The cash or other real property assets to be added to balance the transaction shall not be greater than 25 percent of the value of the county property proposed for exchange.

(c) Unless the public agency to which the property is transferred pursuant to this section and the public agency transferring the property are governed by the same county board of supervisors, the transferring board of supervisors shall publish a notice of its intended action pursuant to Section 6061 at least one week prior thereto in a newspaper of general circulation published in the county.