ROCK RAPIDS — Environmental specialists are determining the effects of a semi crash in the northwestern corner of the state that spilled herbicide and soybean oil into a ditch. The Iowa Department of Natural Resources says the crash happened Tuesday morning about six miles west of Rock Rapids. Officials say an unknown amount of soybean herbicide spilled, as did 150 gallons of soybean oil and 5,000 gallons of water, which reached the ditch and ran into an unnamed tributary of Mud Creek and Rock River.