European earthworms (Lumbricidae) have invaded previously earthworm-free areas of North America where they consume leaf litter, mix soil horizons, and alter nutrient cycling.  Earthworms are introduced through human activities (e.g., logging and angling), but we hypothesize that earthworms use streams to expand their distribution within watersheds.  To test this hypothesis, we conducted field sampling and an inundation experiment on Prince of Wales Island, Southeast Alaska.  We surveyed riparian zones of 11 watersheds of varying timber harvest intensity (0.4-57% watershed area harvested).  We found eight previously unreported invasive earthworm species; and total invasive earthworm density was positively related to percent timber harvest (r²=0.72; p=0.002).  We placed individuals of the three most common invasive species (Dendrodrilus rubidus, Lumbricus rubellus, and Octolasion cyaneum) and one native terrestrial enchytraeid (Mesenchytaeus sp.) in individual perforated cups, submerged them in the Klawock River, AK, and monitored survival daily for eight days.  All invasive species survived complete immersion for that period, whereas 50% of the enchytraeids died by day four.  These results suggest that invasive earthworms use streams as invasional corridors and upstream introductions by timber harvest can affect earthworm densities in downstream riparian areas. Effective control of earthworms in riparian zones will require watershed-level management.