St. Clair County experienced a small decline in the average cost of gas over Memorial weekend. According to AAA, Michigan motorists are seeing a slight increase in pump prices. Fuel is up three cents per gallon on average around the state. However, here in the Blue Water Area, we’re actually witnessing a decline in pump prices by an average of two cents per gallon. The auto group says If gas demand declines post holiday, motorists could see some more stability at the pump.