CLIVE, Iowa (AP) — Officials in suburban Des Moines are seeking answers on what has caused a creek there to turn bright green. The Des Moines Register reports that city officials reached out to the Iowa Department of Natural Resources on Tuesday morning after a Clive resident posted a photo online of a vivid green Walnut Creek.

Department officials have since taken samples of the water, but Clive Assistant City Manager Pete DeKock says the department has not shared the results with city officials. DNR senior environmental specialist Janet Gastineau says the agency has traced the green water back to a lake in the Country Club development, but did not say caused the bright green color.