TransCanada has submitted a second revision of the Nebraska portion of the route for its controversial Keystone XL pipeline, seeking to mollify critics fearful of the oil pipeline’s potential impact on ecologically sensitive terrain and waterways.

The company gave its redrawn route to the state Department of Environmental Quality, moving two segments of the line further east and moving another segment slightly to the west. The changes add 20 miles to the route, bringing the Nebraska portion to 275 miles, TransCanada said.

The Keystone XL pipeline at one point was going to run through the sensitive Sand Hills areas near Valentine, Neb. The pipeline was rerouted to the east, so it will not pass through this area at the Minnechaduza Creek. TransCanada has announced that it will change the Nebraska route again.

Russ Girling, chief executive of the Calgary-based firm, said the company had “refined” its proposed route “based on extensive feedback from Nebraskans and reflects our shared desire to minimize the disturbance of land and sensitive resources in the state.”

However, Jane Kleeb, Nebraska’s leading activist against the Keystone XL route, said in an e-mail that “the new route still risks our land, water and property rights. The new route still crosses high water tables, sandy soil which leads to higher vulnerability of contamination and still crosses the Ogallala Aquifer, the lifeblood of Nebraska’s economy.”

Finding an acceptable route through Nebraska is a critical part of TransCanada’s effort to win approval for the Keystone XL pipeline, which would run from Hardisty in the Canadian province of Alberta to Port Arthur, Tex. The southern leg of the project, starting in Cushing, Okla., has won approval already and construction on that leg has begun. The fate of the northern leg, ending in Steele City, Neb., still hangs in the balance.

Early this year President Obama rejected TransCanada’s initial proposal because he said Congress had imposed a deadline that did not leave enough time to weigh the pipeline proposal, especially the portion that ran through Nebraska’s ecologically sensitive Sand Hills and over parts of the vast Ogallala aquifer that provides drinking and irrigation water in several Great Plains states.

TransCanada now must present its plan to Nebraska’s Department of Environmental Quality, which will give its findings to Nebraska Gov. Dave Heineman. He will approve or deny the plan, which will then go to the State Department of its review.

In its revised filing to the Nebraska DEQ, TransCanada said it would move the Keystone XL route to avoid areas “that exhibit similar characteristics to the Sandhills, even though they are not identified this way in existing literature or agency databases.” It said the areas to be avoided have “features similar to sand dunes and areas with sandy, erodible soils, with a thin organic layer of topsoil. The new re-route minimizes impact on these features.”

In another segment of the line, TransCanada now proposes to put its pipeline east of the town of Clarks to avoid areas where the groundwater is shallow and runs toward the town’s water supply.

In the third altered segment, TransCanada also redrew the route to avoid a water well head protection area.

“Keystone XL will be the safest pipeline built in America,” Girling said in a statement, adding that “TransCanada shares the goal of protecting key water and natural resources with Nebraskans.”

But Kleeb said, “We will not allow middle American to be the middle man for a foreign tar sands pipeline wanting to export their extreme form of energy to the highest bidder.”