In Black Warrior Riverkeeper v. ACOE, decided this week by the 11^th Circuit Court of Appeals, the Court was faced with a quandary.  “On the eve of oral argument”, in a case challenging The Army Corps of Engineers Nationwide Permit 21, which allows certain surface coal mining activities without an individual permit, the Army Corps of Engineers informed the Court that it had significantly underestimated the acreage that would be affected by NWP 21.  Moreover, the Corps acknowledged that this error was sufficiently significant that it needed to revisit NWP 21. 

Thus, the Court had to remand the case so that the Corps could reassess NWP 21 on the correct factual baseline.  So far, so good.  However, this did not address whether the Court should vacate the rule pending the reassessment.  The Court concluded that, because it was possible that the Corps would determine that the error was harmless, it need not vacate the rule (though it did provide that the District Court could order vacatur if it determined that to be appropriate).

The problem is that the aspect of the rule being challenged was a grandfathering provision – The Corps had grandfathered surface mining activities that had already been covered by the prior version of NWP 21.  At the same time, the Corps had determined that, going forward, significant new limits had to be placed on the availability of NWP 21, due to the risk of environmental damage from surface mining.  Thus, the dissent was skeptical that, if the Corps had in fact determined that these activities can cause environmental damage, the Corps could still somehow reasonably determine that the grandfathered activities:

will cause only minimal adverse environmental effects when performed separately, and will have only minimal cumulative adverse effect on the environment.

Good question.  It will be interesting to see what the District Court and the Corps do in response to the remand.