Senator John Thune (R-SD) offered an amendment to S. 744, the Senate Immigration Bill titled the Border Security, Economic Opportunity, and Immigration Modernization Act, which would unnecessarily mandate the construction of hundreds of additional miles of destructive double layered walls along the Southwest border. Additional border walls would lead to more damaging floods by impeding the natural flow of water, and would further fragment habitat, jeopardizing imperiled species like jaguars, ocelots, and big horn sheep. Moreover, reports by the Congressional Research Service and Government Accountability Office have failed to find any evidence that the existing border wall has made a significant contribution to border security. On June 18, the Senate rejected the Thune amendment by a vote of 39-54 (Senate roll call vote 151). NO IS THE PRO-ENVIRONMENT VOTE.