4. The prescribed area, which lies in Highland Region, is the catchment areas of–
(a)all rivers which enter the sea on the west coast of Scotland between, in the north, a point immediately to the south of the Unapool Burn where it enters the sea and, in the south, a point immediately to the south of the River Runnie where it enters the sea; and
(b)all rivers which enter the sea on the east coast of Scotland between, in the north, a point immediately to the north of the River Oykel where it enters the sea and, in the south, a point immediately to the south of the River Oykel where it enters the sea,
in so far as those catchment areas lie within the area delineated by a continuous blue line on the map.