Missouri Department of Natural Resources officials said a dye released Wednesday into Wears Creek was part of a training exercise.
The red, nontoxic dye, called rhodamine, was used to demonstrate how far and fast contamination can spread when spilled or dumped into a flowing stream, according to a department news release.
The department notified Jefferson City officials last week about the dye's planned use in the creek.
DNR officials said rhodamine is harmless to people, animals and the environment. It is widely used in a variety of surface and groundwater tests, such as time-travel testing on streams, evaluating drinking water well construction and to help identify potential sources of water contamination, they noted.