The Olchon is an upland stream that joins the main Monnow just downstream of Longtown. The fishing comprises 1.3 miles of mixed double and single bank, including a small section of the Monnow itself. It is an attractive, fast flowing little stream with a good head of wild trout and a similar diversity of invertebrate life as the Monnow and nearby Escley Brook.
Ideally fished with a 6½-8ft, 2 to 4wt rod.