The Forss river catchment is over twenty miles long, lying between those of the Thurso and the Halladale Rivers in Caithness and Sutherland respectively.
Forss House Fishings, the principal fishery, comprises a stretch of less than four miles running north from Stemster Bridge to the sea.
The Forss is a typical spate river which fishes well in the nine-inch to twenty-four inch range.
Formally a net fishery, it became a rod fishery for the first time twenty-five years ago, when it was turned into a time-share river known as Forss House Fishings.
This comprises some 200 rod weeks between March and the middle of October.
Forss House Fishery is divided into four two-rod beats , two below the Forss Falls which can be fished all season and two above the Falls which are only fishable when water temperatures enable fish to ascend the Falls, normally by the end of April.
There are twenty-six named pools in the fishery, which is capable of producing fish throughout its length in a variety of water levels.
The lowest beat, Beat One, comprises deep channels running through a low lying strath to the rocky sea outfall in Crosskirk Bay .
Beat Two is similar in the lower half but the top end of the beat terminates in the beautiful Forss Falls. The Beat comprises a chain of rock and cobble pools which hold significant numbers of fish when water levels over the Falls restrict passage.
Beats Three and Four of the Forss comprise an immature meandering flow through marshland which has probably the most diverse summer flora of any site in the North of Scotland.
The boundary between these two beats is the picturesque original early 18th century humpy backed Forss Bridge which is a listed structure.