The department of transportation may for highway purposes close off by fill or embankment all water transportation on Camas Slough, a part of the Columbia River extending from a point of land at the confluence of the left bank of the Washougal River and the right bank of the Columbia River to the land on Lady Island with the axis or center line of the embankment being more particularly described as a line bearing south seventy-six degrees (76°), fifty-one a one-half minutes (51 1/2') west from a point; said point being located on the line between section 11 and section 14 and distant approximately 520 feet westerly from the corner common to sections 11, 12, 13 and 14, all situate in township 1 north, range 3 east, W.M. The department shall construct in the fill, at or near the channel of the slough, an opening of sufficient dimensions to allow normal flow of water during the low water period or such opening as may be required or approved by the Corps of Engineers, United States Army.