(environmentalist groups sued U.S. Army Corps of Engineers (COE) claiming that COE violated Clean Water Act (CWA), National Environmental Policy Act (NEPA) and Administrative Procedure Act (APA) when COE issued two nationwide coal-mining waste-discharge permits in 2007 allowing coal companies to fill sections of streams with rock from blasting projects used to uncover coal seams; trial court granted summary judgment to COE; on appeal, court reversed on basis that COE permit issuance arbitrary and capricious because COE did not properly consider impact of past surface mining in approving permits and did not support its finding that coal companies could mitigate stream issues by paying for projects elsewhere; court determined that COE only considered potential effect of mining from 2007-2012 and didn't account for streams filled before 2007; court's opinion largely mute insomuch as COE had already changed permitting process at issue; court's decision stayed for 60 days to allow federal district court in Kentucky to determine impact of decision on existing projects).