“The NWP 21 for surface coal mining activities is revised to impose new limits on stream impacts that may be authorized, consistent with the other NWPs and prohibits valley fills under this NWP,” the USAC said late last week.

It said the updated process was put in place due to public feedback and it leveraged important flexibilities while taking steps to protect wetlands.

While mining operations are now capped at 300 linear feet of stream coverage, local corps officials can waive the limit if the project is deemed to have minimal impact.

The USAC said updated permits would only be necessary for new or expanded activities.

“Operators that relied upon previously verified surface coal mining authorizations but have not yet completed work in waters of the US, may request re-verification under the 2012 NWP 21 of all previously authorized activities,” the agency said.

NWP 21 was one of several nationwide or “general” permits revised or renewed this week under the USACE regulatory program.

Others included NWP 51, regarding land-based renewable energy general facilities and NWP 52 for water-based renewable energy generation pilot projects.

“We believe the set of nationwide permits … encourages innovation and ensures consistency and predictability in meeting the challenges of protecting America's wetlands and aquatic resources,” deputy commanding general for civil and emergency operations Major General Michael Walsh said.

In all, the USAC reissued 48 permits set to expire on March 18 and added two new ones to the list.

All are effective from March 19.

The USACE used NWP 21 for some time in central Appalachia to approve valley fills for mountaintop removal mines instead of performing reviews of permits on an individual basis.

According to regional news outlets including the Register Herald, US District Judge Joseph Goodwin of West Virginia attempted on two occasions to block the use of NWP 21, leading the industry to begin seeking individual permits.