Cal. Water Code § 48401

In case a contract authorized by law has been made between a district and the United States pertaining to the construction, maintenance, or operation of the works of the district, or the delivery or supply of water therefor, no such district shall be dissolved nor shall any proceedings be initiated by a court or otherwise for the purpose of dissolving such district, unless and until the consent in writing of the Secretary of the Interior to such dissolution or proceedings has first been obtained.