If the Transportation Department determines inadequately buried pipelines contributed to past spills, Congress wants the agency to reconsider its pipeline rules and come up with improvements.
After the Yellowstone spill, Exxon re-buried the Silvertip line dozens of feet beneath the riverbed. Other oil companies followed suit after surveys revealed widespread erosion problems for pipelines in Montana.
Montana officials are continuing to investigate the natural resource damages caused by the Silvertip spill. Results are expected possibly in the spring, said Bob Gibson with Montana Fish, Wildlife and Parks.
"After that it will come to a long negotiating process with Exxon Mobil where we say, 'Here's what we think the problem is, and here's what we think is the solution,'" Gibson said.
The natural resource damage assessment is separate from a $1.6 million settlement reached earlier this year between the state and Exxon over the company's water pollution violations.