A challenging clean-up job continues on the Red Cedar River near Menomonie, along Interstate 94.
A truck carrying 24,000 pounds of fertilizer and herbicide in bags crashed into the river during a snowstorm on March 5. Both drivers, from Minneapolis, were killed.
Wisconsin DNR spokesman Ed Culhane said the agency does not know for sure how the nitrogen fertilizer and crab grass herbicide will affect life in the river.
"Some of our scientists are in touch with the manufacturer, and are working with an environmental consultant to learn as much as we can about these chemicals and how they'll react in the river and what kind of damage we may need to look for," Culhane said.
The herbicide is floating to the top, and workers are collecting it.
Much of the fertilizer remains on the river bottom and seems not to be mixing with the cold water.