MILFORD - The DNR and NuStar Energy L.P. have located the source of a petroleum leak from NuStar's buried pipeline running into a stream south of Milford in Dickinson County.
The leak was reported after a farmer who was watering trees Thursday afternoon discovered a sheen and a strong petroleum odor on an unnamed tributary of the Little Sioux River.
The DNR and NuStar traced the diesel fuel leak to a damaged spot in NuStar's buried petroleum pipeline. The pipeline runs underneath a tile line draining a crop field belonging to Todd Gonnerman.
Friday afternoon, the team found more damage to the pipeline at a second tile line location in the field. They are continuing to check places in the field where pipeline and tile lines intersect to see if more of the pipeline is damaged.
NuStar officials and the DNR determined the damage occurred last fall while the field was being tiled.
"This is a good example of why it's so important to call Iowa One Call before any digging," said Jennifer Christian, a DNR environmental specialist at the scene.
Christian says clean up of the site will take a while and possibly involve excavating contaminated soil, flushing the tile line, and cleaning up two miles of stream and a farm pond. A team from NuStar continues working to contain and recover diesel from the creek and pond.
The DNR will continue to monitor the spill and its clean up, and will consider appropriate enforcement action.
Iowa One Call is a free service required for all excavations. Call 800-292-8989 or 811 at least 48 hours prior to excavating.
Christian said because they found only a few dead fish at the farm pond, the fuel leak is probably not the cause of death. Recent high temperatures or possibly a drop in oxygen levels are more likely causes.