The Montana Stream Access Law says that anglers, floaters and other recreationists in Montana have full use of most natural waterways between the high-water marks for fishing and floating, along with swimming and other river or stream-related activities. In 1984, the Montana Supreme Court held that the streambed of any river or stream that has the capability to be used for recreation can be accessed by the public regardless of whether the river is navigable or who owns the streambed property. On January 16, 2014, the Montana Supreme Court, in a lawsuit filed by the Public Land/Water Access Association over access via county bridges on the Ruby river in Madison County, Montana reaffirmed the Montana Stream Access Law and the public's right to access rivers in Montana from public easements.

The Flathead River, in the northwestern part of the U.S. state of Montana, originates in the Canadian Rockies to the north of Glacier National Park and flows southwest into Flathead Lake, then after a journey of 158 miles (254 km), empties into the Clark Fork. The river is part of the Columbia River drainage basin, as the Clark Fork is a tributary of the Pend Oreille River, a Columbia River tributary. With a drainage basin extending over 8,795 square miles (22,780 km2) and an average discharge of 11,380 cubic feet per second (322 m3/s), the Flathead is the largest tributary of the Clark Fork and constitutes over half of its flow.