(a) The department shall examine all conduits. If, in the opinion of the department, a screen is necessary to prevent fish from passing into the conduit, the department shall order the owner of the conduit to install a screen.
(b) Except as provided in Sections 5987, 5988, and 5989, one-half of the expense of constructing or installing a screen shall be paid by the owner of a conduit and one-half by the department.