The National Environment Management Authority (Nema) is tracking down manufacturers and suppliers of plastic bags in the county.
County Nema Director Joseph Kopenjo said his officers had registration numbers of vehicles said to be supplying the bags in the area.
"We are monitoring the situation and will arrest anyone selling the outlawed bags," he said.
A spot check by The Standard established traders were still using the bags.
“We cannot tell you who supplies the banned bags to us. We use them to wrap peeled sugarcane. Our customers, especially motorists, prefer when we peel and chop the sugarcane,” said Nicasio Njeru.