- Pine Hollow, OR offers several convenient options for RV dumping and waste disposal.- You can find dump stations at Mt. Hood National Forest - Lost Lake Campground, KOA - Cascade Locks / Portland East KOA Campground, and Cascade Locks Marine Park.- These dump stations provide facilities for dumping black water and gray water, as well as access to fresh water for flushing tanks.- Additionally, they usually have an RV trash bin for disposing of any other waste.- Make sure to bring your hose for flushing tanks when using these dump stations.