An environmental review of the project, first proposed by TransCanada Corp. in 2008, concluded that the pipeline running through an alternative route would have "minimal" risk involved, The Wall Street Journal reported.
The company's first route, which put the pipeline through the environmentally delicate Sand Hills region, was rejected. The second route, which won state approval this week, circumvents the region, although it crosses an important aquifer that is the source of water for human consumption and for irrigation.
Environmental groups are now lobbying for Republican Gov. Dave Heineman to reject the state's environmental review. He has 30 days to reject or approve the report and said this week he would take several weeks to review it.
"We have made significant strides to work with Nebraskans to identify the safest route possible for this pipeline project," TransCanada spokesman Grady Semmens said.
Work has already begun on the southern section of the pipeline, which will supply the Gulf States region with Canadian tar sands oil that is so thick it must be diluted to flow through a pipeline.
The northern pipeline section, if approved, would start in Alberta, Canada, and end in Steele City, Neb.