- If you need to dump black or gray water, Hamburg, Iowa has several options in the surrounding areas.- You can visit Victorian Acres RV Park and Campground, Indian Cave State Park, Johnson County Fairgrounds, or Louisville State Recreation Area to dispose of your waste properly.- Most locations provide fresh water and a hose for flushing tanks. Additionally, trash bins are available for disposal of any solid waste.- Make sure to follow all regulations when disposing of your waste at these locations.