Inspection of work as it progresses.
During the progress of any work to be paid for from the proceeds of any bond issue certified as in this chapter provided, the director of ecology shall make or cause to be made, from time to time, at the expense of the district, such inspection of the work as may be necessary to enable the said department to know that the plans approved by the director are being carried out without material modification, unless such modification has been approved by the director.