U.S. Army Garrison Yuma Proving Ground Laguna Army Airfield (PWS ID No. AZ0414361) public water system failed to meet the drinking water maximum contaminant level ( MCL ) for arsenic since September 2007 to the present. EPA Region 9 administrative order requires the U.S. Army Garrison to provide EPA Region 9 with plans and schedules to meet the arenic MCL by June 30, 2012.