Superficially, the federal government is upholding the rights of the Indian Tribes to claim all surface and subsurface waters of the western one-third of the state of Montana. In reality, the federal government is taking a 170-year-old treaty, expanding its meaning, and using it as a tool to commandeer everyone's water.

Whether you live in California or New York, the reason this is important should be obvious to you.

Government overreach has become a way of life. The paradigm has shifted, and now, people barely bat an eye when the government steadily removes the rights enumerated under the Constitution. Today, it may not matter to you because this is happening in Montana. Perhaps it will matter when the federal government comes to commandeer your drinking supply, crops, arable farmland, etc. 

The Hellgate Treaty of 1855 was the document used to create the Flathead Indian Reservation. The treaty (under Article III) stipulates that the tribes have the "right of taking fish," and this right refers to waters, not on the reservation.