BISMARCK, N.D. (AP) -- Officials say no oil from a pipeline rupture in northwestern North Dakota has been found so far in surface or groundwater. North Dakota water quality director Dennis Fewless says state and Tesoro officials are closely monitoring the estimated 20,000-barrel spill that covers an area the size of seven football fields near Tioga. The spill was found by a farmer on Sept. 29. Fewless says a thick layer of clay beneath the spill site is acting as a natural barrier to any water sources below.
He says monitoring wells have been placed on the perimeter of the spill area to check for any oil that may escape.