The board of supervisors within thirty days after organizing shall employ an attorney to act for the district and to advise the board. Such employment shall be evidenced by an agreement in writing which, as far as possible, shall specify the amount to be paid to the attorney for all services and expenses. Such attorneys shall conduct all legal proceedings and suits in court when the district is a party or interested and shall in all legal matters advise the board of supervisors and all officers, employees or agents of the district and board and generally look after and attend to all matters of a legal nature for the board and district. When the board may deem it necessary they may, by and with the advice of their attorney and under the like terms and conditions as above set forth employ another attorney or attorneys.