A winter survey of a small upland river system, the Clogh River, Northern Ireland, was conducted to appraise the macroinvertebrate community in light of a reportedly declining fishery. Plecoptera were more abundant at the higher elevation sites; Ephemeroptera were more abundant at lower elevations; and Trichoptera were widely distributed but never abundant. With reference to functional feeding groups, grazers/scrapers and collectors were widely distributed at all elevations, while most shredders were found at higher elevation sites. The transition from dependence on allochthonous to autochthonous energy inputs, based on the composition of the community, appeared to occur approximately at the 1–2 stream order boundary. This is probably due to the sparse riparian vegetation and lack of shading on most stretches of this river.