By Corrie Plant ( May 2, 2018, 4:23 PM EDT) -- The U.S. Supreme Court recently heard oral argument in Washington v. United States, a case involving the off-reservation fishing rights of 21 Native American tribes in the Pacific Northwest. At issue are culverts built by the state of Washington under roadways it constructed across salmon-bearing streams. The tribes allege the culverts allow the passage of water, but not the passage of salmon, and thus are an unlawful interference with tribal fishing rights under its longstanding treaties with the United States. Specifically, the issue is whether the treaties guarantee the Tribes protection of salmon populations, i.e., habitat protection, or instead if they only protect the tribes' right to a share of available fish. This question has not previously been answered by the Supreme Court....