Colorado tribes are worried that a U.S. Supreme Court ruling last month against the Navajo Nation in a Colorado River water rights case may narrow the federal government’s broad, historic responsibility to provide them with aid. In Navajo Nation vs. Arizona Dept. of the Interior, the tribe was seeking to sue the federal government to require it to assess the tribe’s water rights along the Colorado River and help to create a plan to develop them for the 170,000 tribal members who live there.