ISLE DU BOIS CREEK. Before the construction and filling of Lake Ray Roberts, Isle Du Bois Creek rose at the confluence of Jordan Creek and Range Creek, four miles southwest of Collinsville in southwestern Grayson County (at 33°30' N, 96°55' W). The stream ran southwest across southeastern Cooke County and northern Denton County for seventeen miles before reaching its mouth on the Elm Fork of the Trinity River, 4½ miles northeast of Green Valley in north central Denton County (at 33°22' N, 97°02' W). When the Elm Fork of the Trinity River in Denton County was dammed to form Lake Ray Roberts, the area through which Isle Du Bois Creek flowed was inundated. The local terrain is generally flat and is surfaced by clay and sandy loams that support water-tolerant hardwood trees, conifers, and various grasses.