All claims for services rendered, expenses incurred or materials or supplies furnished under the direction of the state engineer and which are payable from the funds appropriated for the prosecution of the work under his direction and supervision, shall be approved by the state engineer and properly vouchered and filed with the secretary of finance and administration, who shall, if he finds the same to have been incurred in accordance with law, audit and allow such claims and issue his warrant on the treasurer in payment thereof.