A proposed natural gas pipeline in the Gunpowder River watershed is raising alarms among environmentalists, who worry that its construction would disrupt one of the East Coast’s finest trout rivers as well as drinking water for the Baltimore metropolitan region.

Columbia Gas, a subsidiary of Texas-based energy giant NiSource, wants to build a 21.5 mile gas line that would extend from Owings Mills in Baltimore County to Rutledge in Harford County. The 26-inch natural gas line would follow Columbia’s existing pipeline for 16.5 miles, then extend an additional five miles. Per a request from the Department of Natural Resources, it will go around Gunpowder Falls State Park instead of through it, which is one reason it needs the extension.

The $180 million project could cross 70 small waterways in one of Maryland’s most pristine river valleys, which supplies water to the Loch Raven reservoir, the drinking water source for 2 million people. Among the areas it would affect are ones many residents treasure — the trout stream Beaver Dam Run, the Genesee Outdoor School, the lush Greenspring Valley and the popular Oregon Ridge Nature Center and Torrey C. Brown Trail.

Columbia wants the line to enhance reliability for its customers to the north and east of Baltimore. It says it needs to build the parallel line and the extension must have a “loop pipeline” so it can provide a backup source of supply in the event of outages. It also wants to be able to properly maintain the infrastructure with no service disruptions, which is easier to accomplish with a loop system.

Federal government officials have long touted the benefits of pipeline integrity, and President Obama has been a proponent of natural gas, which is considered to be a cleaner-burning fuel than coal and more readily available than oil. The Columbia pipeline received approval from the Federal Energy Regulatory Commission in late November.

But Columbia still needs two key permits — a wetlands and waterways permit from the U.S. Army Corps of Engineers and a state water quality certification permit from the Maryland Department of the Environment. The two agencies conducted two joint public hearings on the permits last spring. Residents with homes along the pipeline testified about many concerns, among them losing their yards, being forced to cut down their trees and possibly compromising their well water and septic fields. Several representatives of the building trade unions testified in favor of the project, which would bring construction jobs to the area.

Both the general location and the specific type of construction concern environmental advocates. Columbia is proposing to use an open-trench method to install the pipe, according to hearing documents. That method would disturb approximately 100 feet of ground for the 26-inch pipeline, according to Gunpowder Riverkeeper Theaux M. Le Gardeur. In some parts, a partial buffer already exists. Though the company would replant about 50 feet worth of that buffer, the Gunpowder would forever lose mature trees and important vegetation that provide stormwater benefits and shade for brook trout. Instead of trees, Le Gardeur fears, there would be shrubs and grass.

Construction of the pipeline will impact 1.31 acres of streams, 4.52 acres of nontidal wetlands, 3.2 acres of nontidal wetland buffer and 4.86 acres of 100-year floodplain. Furthermore, MDE officials stated the construction would permanently convert 0.83 acres of forested non-tidal wetlands to “emergent wetlands” and permanently impact 0.72 acres of the non-tidal 25-foot buffer. But the Corps has only required Columbia to mitigate for the 0.83 acres, and they would do that off-site.

Walking the corridor of the Torrey C. Brown Trail on a recent morning, Le Gardeur pointed out some of the existing right of ways for the Columbia pipeline. Large swaths of trees had been cleared, the hillsides denuded, with a yellow pipe sticking out of the ground and an unmistakable odor of natural gas.

“They’re not going through a meadow here, not by any stretch,” said Le Gardeur, an avid fisherman who also owns a shop, Backwater Angler, near the trail.

Maryland Department of Natural Resources officials are also concerned about the digging. They’ve pushed the permitting agencies to require horizontal directional drilling, a time-intensive technique that bores a hole for the pipeline and would spare much of the landscape from disruption. Nationwide, many projects have moved to horizontal directional drilling to protect fish habitat and streams, but some companies don’t like the added expense.

In a seven-page letter to the Federal Energy Regulatory Commission, Deputy Natural Resources Secretary Frank Dawson asked the commission to reconsider its permit decision, and said his department had consistently recommended horizontal drilling for the parts of the pipeline that crossed sensitive trout streams.

“From the onset, when DNR first learned about this project and throughout the various comments provided by the Department, our consistent and strong recommendation has been that the most sensitive stream crossings should be conducted with HDD (horizonatal direction drilling), and not open trenching.”

Dawson quotes his own fisheries staff in the letter: “We cannot afford to risk any of these prominent wild trout resources contained in these central Maryland watersheds. They are…the only remaining stronghold for trout in the Eastern portion of our state.”

Dawson also wants Columbia to enact a plan to control the Didymo algae, also known as rock snot, that has spread around the area. The agency has worked with Le Gardeur to control it through a network of wader-washing stations, but Dawson worries that the algae could attach to equipment and spread.

Both Dawson and Le Gardeur say the Environmental Assessment that Columbia completed is not comprehensive. Both are asking FERC to require a more thorough Environmental Impact Statement.

Le Gardeur said he believes the entire notification process is flawed, because the Maryland Department of the Environment and the Army Corps of Engineers focused its notices on impacts to trout waters, as opposed to drinking water. The ads in the newspapers announcing the public meeting made no mention of

drinking water.

MDE officials denied Le Gardeur’s request to restart the public process because of the omission. An MDE spokesman said they did not know when they would make a permit decision, but that it would likely not come before March.

Le Gardeur said many more residents from the region would have testified at the hearing had they known about the drinking water connection.

“The drinking water supply aspect has not really been discussed in a public forum,” Le Gardeur said. “One hundred percent of the drinking water in north Baltimore and Harford County are dependent on these surface water streams. They are only being given a cursory glance.”

Against all odds, it seems, the Gunpowder has remained fairly pristine. The current pipeline runs through some of the watershed’s prettiest parts, including Oregon Ridge Park and the busy Torrey Brown C. Trail. Suburbs encroach, and the city line is just a few miles away. Yet Baltimore County’s decision to establish an urban/rural demarcation line nearly a half century ago and restrict development north of Hunt Valley likely saved the river, and brings millions of dollars in economic impact each year as anglers from all over the country come to fish along its banks.

But studies have shown that a river reaches a tipping point when more than 10 percent of its watershed becomes impervious through the development of homes, roads, and other hard surfaces. For trout, which are especially sensitive, problems can turn up when a watershed is 5 percent impervious. The open-trench digging, Le Gardeur fears, would put certain streams over the edge — clogging small, coldwater habitat with sediment and stripping its banks of mature vegetation.

Some legislators and homeowners also have safety concerns, especially after a Columbia natural gas pipeline exploded in Sissonville, WV, last year and destroyed several homes. Sissonville residents are suing Columbia, alleging the company did not maintain the pipeline properly.

Maryland Sen. Bobby Zirkin said he and his colleagues put in more than a dozen bills to ensure pipeline safety last year. None of them went anywhere, he said, because Columbia and its strong lobbyists blocked them.

“When we wanted to look at alternatives for the environment in pipelines, when we had legislation that other states had done, there was one company standing at the table to kill those bills, one: Columbia,” Zirkin told the crowd at the Owings Mills public hearing.

Zirkin added that he was not a scientist, not an environmental engineer, and not the best person to speak to trout impacts and the right kind of drilling methods. Still, he said, it was clear to him that a pipeline through the county’s most pristine treasures was not going to end well.

“I can tell you in general that this is wrong. They should be forced to look at other alternatives. You know, for the representative from the federal government that’s here, they should be forced to actually inspect their lines so they don’t just blow up because no one’s looking at it. And I guess as my representative from the Department of the Environment and Army Corps of Engineers, I implore you to make these folks do more.”

When he was done, the crowd applauded.