The secretary shall (1) be custodian of the records of the district and of its corporate seal, (2) assist the board in such particulars as it may direct in the performance of its duties, (3) attest, under the corporate seal of the district, all certified copies of the official records and files of the district that may be required of him by sections 46-501 to 46-573, or by any person ordering the same and paying the reasonable cost of transcription, and any portion of the record so certified and attested shall prima facie import verity, and (4) also serve as treasurer of the district unless a treasurer is otherwise provided for by the board. The board may also employ a chief engineer, an attorney, and such other agents and assistants as may be necessary and provide for their compensation which, with all other necessary expenditures, shall be taken as a part of the cost or maintenance of the improvement. The chief engineer shall be superintendent of all the works and improvements. He shall make a full report to the board each year, or more often if required by the board, and may make such suggestions and recommendations to the board as he may deem proper. The secretary and treasurer, and such other agents or employees of the district as the board may direct, shall furnish corporate surety bonds, at the expense of the district, in such amount and form as may be fixed and approved by the board conditioned for the faithful performance of their respective duties.