Location

Hi, Along the Upper Golf Creek right behind my property (And not part of my property) there is a lot of Himalayan Blackberry, Sweet Violet, Creeping Buttercup, and English Ivy growing on trees. Would love to help clearing them up but since it's not on my property and not sure how to find out if it belongs to county or other private owners, would love some guidance and physical help as it is too much for just me to handle. My home address is 345 SW Breeze Ct, Portland, 97225; Washington County