is an artificial reservoir
in the Pentland Hills
, Scottish Borders
, 3 km west of West Linton
, and 26 km south west of Edinburgh
. It forms part of the Lothian region water supply and is located 320 m above sea level.
Due to its popularity with Pink-footed Geese (Anser brachyrhynchus) it has been designated as a Special Protection Area and a Ramsar site.