4. The prescribed area, which lies in Highland Region, is the catchment areas of all rivers which enter the sea on the west coast of Scotland between–
(a)in the north, a point immediately to the north of Achriesgill Water where it enters the sea, and
(b)in the south, a point immediately to the south of Abhain an Loch Bhig where it enters the sea,
and is delineated by a continuous blue line on the map.