Mont. Code Ann. § 85-7-1932

Navigation may not be impeded by the operation of this chapter. A vested interest in or to any mining or agricultural water rights or ditches or in or to any water rights, reservoirs, or dams now used beneficially in connection with any mining or agricultural industry or by persons purchasing or renting the use of the interest or in or to any other property used, directly or indirectly, in carrying on or in promoting the mining or agricultural industry may not be affected by or taken under this chapter, except that rights-of-way may be acquired over the mining or agricultural property or interest. The right of eminent domain, as provided in Title 70, chapter 30, is not otherwise affected by the provisions of this section.