The sequence of qualitative and quantitative changes in the chironomid fauna of Laurel Creek Reservoir over the thirteen years of its existence are presented. There was a substantial decrease in the average numerical abundance Pram 1967 (6303m−2) to 1968 (3373m−2), and it has remained stable since (3166m−2in 1975, 2856m−2in 1980). There have been distinct changes in the faunal numerical abundance, although the genera have remained the same. In 1967, the Chironomini (Chironomus>Glyptotendipes) comprised 95% of the total throughout the year. In 1968, the Chironomini dominated (68%) the Tanytarsini increased (24%) and the Tanypodinae (6%) and Orthocladiinae (2%) remained low. In 1975, the Chironomini (Chironomus>Glyototendipep≈Cladopelma) (72%) and the Tanypodinae (Procladius) (21%) increased, the Tanytarsini decreased (5%) and the Orthocladiinae remained low (2%). By 1980, the Tanypodinae (Procladius) had become dominant (60%) while the Chironomini (Chironomus>Cladopelma>Glyptotendipes) had decreased (38%). The Tanytarsini and Orthocladiinae were insignificant (1% each). The decreased standing stock and changes in the dominance hierarchy of the chironomid fauna are associated with changes in the trophic level of the substrate conditions and bottom oxygen levels of the reservoir.