This portion of the data release presents aquatic invertebrate abundance data from samples collected in the Elwha River estuary, Washington, in 2007 and 2013 (no associated USGS Field Activities numbers because data were collected predominantly by biologists from the Lower Elwha Klallam Tribe). Replicate benthic samples were collected at 18 locations throughout the estuary complex using a petite Ponar grab sampler (appx. 2400 mL sample) and sorted through a 500-micron sieve. Samples were fixed in 10 percent formalin for 3 to 5 days before being transferred to 70 percent ethanol until processing. Individuals were identified to the lowest possible taxonomic resolution, but are grouped according to insect Orders in the data for consistency (unless otherwise noted in the attributes). The locations of samples were determined with a hand-held global positioning system (GPS). Aquatic invertebrate abundance data (including fractions of individuals) are provided in a comma-delimited spreadsheet (.csv).