The Blue Hole Creek basin (1652 ha) is located in an area of Pennsylvania that is historically high in wet deposition of sulfates and nitrates. Five stations on Cole Run (chronically acidified) and one on Blue Hole Creek (episodically acidified) were sampled twice seasonally—once at base flow and once at high flow. Total iron, aluminum, and sulfate trended toward a direct relationship with discharge, while pH and alkalinity exhibited an inverse relationship. Stations with higher pH values were linked with the Mauch Chunk geologic formation and Fluvaquents soil series, while those with lower pH were linked with the Pottsville geologic formation and the Brinkerton, Cookport, and Rayne-Gilpin soil series. Fewer macroinvertebrates were collected from the episodically acidified station than at any of the chronically acidified stations on 71% of the sample dates. Although the number of taxa was similar between stations (n=16-23), more taxa were unique to Cole Run than to Blue Hole Creek. Shredder and collector functional groups dominated in Cole Run, while in Blue Hole Creek functional groups were more balanced, or dominated by predators or collectors depending on season. No clear patterns were discerned for season or flow. High flows, however, tended to produce higher diversity values at stations usually dominated by a single taxon. Despite chronic acidification, stations on Cole Run showed diversity and equitability values similar to, and occasionally exceeding, those of the episodically acidified stream.