In 1998, approximately 235 km of Harlequin Duck stream surveys were conducted on six streams, with the majority of effort focused on four Lower Clark Fork streams (Rock Creek, Swamp Creek, Marten Creek, Vermilion River). Additional streams surveyed were Trail Creek (North Fork Flathead River drainage) with one pair survey and one brood survey, and Upper McDonald Creek (Glacier National Park) with one brood survey. On the Lower Clark Fork streams, stream flow was significantly below normal during early-May pair surveys. A minimum of 24 adult Harlequins (13 males, 11 females) was seen on 3 streams. These included Marten Creek (7 pairs, 2 males), Rock Creek (1 pair, 1 male, 1female), Vermilion River (2 pairs) and Swamp Creek (no birds). The number of birds observed was about average for all streams, although Swamp Creek again had no birds. Brood surveys were conducted during July and early August 1998. Seven broods were observed on the Lower Clark Fork streams (2 each on Marten Creek and Vermilion River, 3 on Rock Creek), successfully producing a maximum 11 young on Marten Creek, 6 young on Vermilion River, and 13 young on Rock Creek. Age of broods indicated that nesting among these streams was initiated over a period of at least three or four weeks. New birds were banded on Marten Creek (2 males, 2 females, 5 juveniles), Vermilion River (1 female, 3 juveniles) and Rock Creek (2 juveniles). One third-year female, banded as a juvenile on Swamp Creek in August 1995, was observed paired in May 1998 on Rock Creek, an inter-stream movement of ca. 21 km, and the first documented between these two streams. Stream survey results from other areas were as follows. On Trail Creek (N. Fork Flathead drainage) 3 pairs and 1 male were counted on 14 May, 1 female (already banded) with a brood of 1 juvenile was captured and banded on 7 August. On McDonald Creek in Glacier National Park, park personnel reported a maximum of 8 pairs in spring. During brood surveys, 2 females (1 already banded) with 2 broods (8 juveniles) were captured and banded on 6 August. Three additional broods (3 females, 13 juveniles) were counted on 17 and 19 August by park personnel, and 2 female (1 already banded) and 12 juveniles were banded.