(1) As provided in the Montana Water Use Act of 1973, sections 85-2-302 and
85-2-402, MCA, all new surface water diversions and changes in place of
diversion after July 1, 1973, require permits or approval, respectively, from
the department. Within designated floodways, the department shall review each
proposed diversion and change in place of diversion to determine if flood flows
may be affected.
(2) If it appears that a proposed diversion
or change in place of diversion may significantly affect flood flows, the
department may require the applicant to provide additional information and to
apply for a permit with the permit issuing authority under Title 76, chapter 5,
MCA, as amended.
(3) A permit under Title 76, chapter 5,
MCA, as amended, shall not be granted if in the judgment of the permit issuing
(a) the proposed diversion will increase the upstream elevation of the base flood a
significant amount (0.5 of a foot or as otherwise determined by the permit
issuing authority) ;
(b) the proposed diversion is not designed and constructed to minimize potential
erosion from a base flood; and,
(c) any permanent diversion structure crossing the full width of the stream channel is
not designed and constructed to safely withstand up to a base flood.