WASHINGTON (AFP) – The Environmental Protection Agency has proposed an unprecedented veto to restrict or prohibit mining at a major proposed US mountaintop removal coal mining site.

If the veto is finalized, it would invalidate a permit first issued in 2007 for the Army Corps of Engineers at the Spruce No. 1 surface mine in southern West Virginia.

In explaining its decision, the EPA said Friday the Arch Coal Inc. mine would pollute surrounding water, fill over seven miles (11 kilometers) of stream, would cause "unacceptable" harm to wildlife and "directly impact" some 2,278 acres (922 hectares) of forest.

A rare step in three decades of mountaintop mining in West Virginia, Kentucky and Virginia, the decision was the first time the EPA has proposed to veto a mine that already had received a permit.

It was the 12th time the agency has used its veto power for any project since the 1972 Clean Water Act became law.

"Landscape and site-specific assessments reveal that past and current mountaintop mining has caused substantial, irreplaceable loss of resources and an irreversible effect on these resources within the Coal River basin," the EPA said in a statement.

In its summary of its proposal on the Spruce No. 1 mine, the agency said that "applying the lessons of the past, we now know that failure to control mining practices has resulted in persistent environmental degradation in the form of acid mine drainage and other impacts that cost billions to remedy."

Environmentalists say mountaintop mining, which consists in removing entire coal seams are removed from the tops of mountains, pollutes streams and valleys, dumps toxic mining byproducts and disfigures the landscape.

Arch Coal condemned the EPA's action and vowed to "vigorously defend the Spruce permit by all legal means."

Its stock prices closed 20 cents lower at 22.69 dollars on Friday.

Environmental groups, meanwhile, hailed the EPA's move.

"The best available science tells us that proposed mines like the massive Spruce Mine would pollute waterways, destroy mountains and devastate communities," the Sierra Club's director of environmental quality Ed Hopkins said in a statement.

According to Business Week, mountaintop mining accounts for six percent of US coal production. Coal supplies about 50 percent of US electricity needs.