A coalition of enviros filed suit yesterday to force the U.S. government to do a better job of protecting endangered species and habitat along the lower Colorado River where it flows south toward Mexico and the Gulf of California. The ecological health of the area has deteriorated because seven upstream states divert so much water from the river. The federal government has teamed up with Arizona, California, and Nevada to launch a program aimed at restoring habitat along the lower Colorado from the Hoover Dam to the Mexico border, but the enviros say the program doesn’t go far enough and violates the Endangered Species Act because it doesn’t even consider the possibility of allowing more water to flow downstream. Fights over Colorado River water are among the most contentious and politically volatile in the Western U.S.