Helena Valley is the name of a river valley and a locality in the foothills of the Darling Scarp in Perth, Western Australia. The river valley is the centre of the catchment of the Helena River and extends from the edge of the Darling Scarp where Boya, Gooseberry Hill and Helena Valley define the "mouth" of the valley that opens to the Swan Coastal Plain, east and …Helena Valley is the name of a river valley and a locality in the foothills of the Darling Scarp in Perth, Western Australia. The river valley is the centre of the catchment of the Helena River and extends from the edge of the Darling Scarp where Boya, Gooseberry Hill and Helena Valley define the "mouth" of the valley that opens to the Swan Coastal Plain, east and south east past Mundaring Weir and Lake C.Y. O'Connor to its origins in the region of Mount Dale.