Coal operators cannot evade the Clean Water Act by building sediment-treatment ponds just downstream from strip mine valley fills, a federal judge ruled Wednesday.

U.S. District Judge Robert C. Chambers essentially outlawed the common coal industry practice of turning small stream segments downstream from fills into waste treatment systems.

In a 26-page decision, Chambers concluded that the Clean Water Act protects parts of streams where mine operators traditionally build sediment-control ponds. The judge also said the law protects small segments of streams between those ponds and the bottom of valley fills.

The U.S. Army Corps of Engineers, Chambers declared, “has no authority under the Clean Water Act to permit the discharge of pollutants into these stream segments.”

Wednesday’s ruling is the second time in three months that Chambers has dealt a major blow to the coal industry with a ruling to more strictly regulate mountaintop removal mining.

In March, Chambers blocked four corps permits for Massey Energy operations, ruling that agency officials had not fully evaluated the potential environmental damage before approving the operations. That ruling is being appealed.

The new ruling is part of the same case, a lawsuit brought against the corps by the Ohio Valley Environmental Coalition, Coal River Mountain Watch and the West Virginia Highlands Conservancy.

In mountaintop removal, coal operators blast off entire hilltops to uncover valuable, low-sulfur coal reserves. Leftover rock and dirt is dumped into nearby valleys, burying streams.

Generally, coal operators allow the water that discharges from the toe of a valley fill to flow through a stream segment to a sediment pond that is built inside a streambed farther downstream. In the sediment pond, solids settle to the bottom and, theoretically, clear water flows out into the stream.

State and federal regulators judge whether the mining operation complies with its water pollution limits by testing the water that flows out of the sediment ponds.

Coal operators cannot evade the Clean Water Act by building sediment-treatment ponds just downstream from strip mine valley fills, a federal judge ruled Wednesday.

U.S. District Judge Robert C. Chambers essentially outlawed the common coal industry practice of turning small stream segments downstream from fills into waste treatment systems.

In a 26-page decision, Chambers concluded that the Clean Water Act protects parts of streams where mine operators traditionally build sediment-control ponds. The judge also said the law protects small segments of streams between those ponds and the bottom of valley fills.

The U.S. Army Corps of Engineers, Chambers declared, “has no authority under the Clean Water Act to permit the discharge of pollutants into these stream segments.”

Wednesday’s ruling is the second time in three months that Chambers has dealt a major blow to the coal industry with a ruling to more strictly regulate mountaintop removal mining.

In March, Chambers blocked four corps permits for Massey Energy operations, ruling that agency officials had not fully evaluated the potential environmental damage before approving the operations. That ruling is being appealed.

The new ruling is part of the same case, a lawsuit brought against the corps by the Ohio Valley Environmental Coalition, Coal River Mountain Watch and the West Virginia Highlands Conservancy.

In mountaintop removal, coal operators blast off entire hilltops to uncover valuable, low-sulfur coal reserves. Leftover rock and dirt is dumped into nearby valleys, burying streams.

Generally, coal operators allow the water that discharges from the toe of a valley fill to flow through a stream segment to a sediment pond that is built inside a streambed farther downstream. In the sediment pond, solids settle to the bottom and, theoretically, clear water flows out into the stream.

State and federal regulators judge whether the mining operation complies with its water pollution limits by testing the water that flows out of the sediment ponds.

Environmental groups alleged that the stream segments between the fills and the ponds — know by some regulators as “silt snakes” — are “waters of the United States” subject to federal pollution limits.

“Compliance with water quality standards is therefore required not only at the outlet of the sediment pond, but also upstream starting at the toe of the valley fills,” the environmental group lawsuit argued.

In his ruling, Chambers agreed.

Bill Raney, president of the West Virginia Coal Association, said that the industry would appeal to the 4th U.S. Circuit Court of Appeals in Richmond, Va.

“It’s absolutely astounding to me,” Raney said of Chambers’ ruling. “Here’s a judge outlawing a practice that has been in place for almost four decades.”

Chambers noted that in-stream sediment ponds are a long-standing industry practice. But, he found there was little legal basis for the practice. The corps’ defense, Chambers said, “appears to be ... a post hoc rationalization for the purposes of this litigation.”

Joe Lovett, a lawyer for the environmental groups, praised the judge’s decision.

“The Clean Water Act has prohibited this kind of activity since it was passed,” Lovett said. “The agency simply never enforced it.

“The mining industry has to change its practices to comply with the Clean Water Act,” he said. “It’s an ingenious industry, and it can find a way to do that.”