Mont. Code Ann. § 85-7-2167

Where any lands in any district are sold or transferred, either by deed, mortgage, foreclosure sale, or otherwise, such sale or transfer shall include the water belonging to and appurtenant to the land, whether or not the same is expressly stated in the deed, instrument of transfer, or decree, and such land shall be liable to special tax or assessment the same as if such sale or transfer had not been made.