Some Question Tesoro Spill Data

BISMARCK, N.D. (AP) — Scientists are questioning the methodology used in estimating the amount of crude oil that recently leaked from a ruptured pipeline into a northwestern North Dakota wheat field.

Tesoro Corp. says it came up with its more than 20,000-barrel spill estimate on ground analysis. But oil spill experts say a more accurate assessment would likely come from analyzing pipeline flow data.

Farmer Steve Jensen discovered the oil spill the size of seven football fields while out harvesting wheat on Sept. 29.

Tesoro first estimated the spill at its underground pipeline near Tioga at 750 barrels. But it later bumped the estimate to 20,600 barrels, making it one of the largest spills in North Dakota history.