The Benton County Treasurer's Office has CLOSED the drop boxes at the Prosser Courthouse, the Benton County Administration building in Kennewick, and Richland City Hall for property tax payments. The drop boxes are designed for property tax payments made by check. (NO CASH payments) Benton County Kennewick Office: CLOSED 7122 W Okanogan PL #E110, Kennewick, WA 99336 Benton County Prosser Courthouse: CLOSED 620 Market St, Prosser, WA 99350 Richland City Hall:   CLOSED 625 Sw