Data from 10-day sediment toxicity tests of bed sediments from the Niagara River area of concern and tributaries, Niagara and Erie County, New York. Specifically, the data was used to compare the survival and growth of two macroinvertebrate species in sediments from study sites and laboratory controls. Results are from 10-day sediment exposures of two test species, Chironomus dilutus and Hyalella azteca. Bed sediments were collected from depositional areas using either a petite Ponar (0.03 square meter) dredge or a stainless steel sediment scoop. At each site, approximately five grabs or scoops were composited into a bucket, mixed, and a 4-liter (L) subsample was stored in a polyethylene container. Sediment toxicity testing were then conducted by a contract laboratory to quantify toxicity with the dipteran, Chironomus dilutus, and the amphipod, Hyalella azteca, during 10-day survival and growth bioassays following USEPA test methods 100.2 and 100.1, respectively. U.S. Environmental Protection Agency, 2000, Methods for measuring the toxicity and bioaccumulation of sediment associated contaminants with freshwater invertebrates. Second edition: U.S. Environmental Protection Agency, Office of Research and Development EPA 600/R-99/064.http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=30003SBA.TXT. The data include the year, site ID, and six columns of results from 10-day sediment exposures of two test species, Chironomus dilutus and Hyalella azteca. The following endpoints were measured for each species following the 10-day exposure: percentage of organisms surviving (hereafter survival), average ash-free dry weight of the surviving organisms (hereafter growth), and average ash-free dry weight of the surviving organisms divided by the initial number of organisms (hereafter biomass). Companion to this report: George, S.D., Baldigo, B.P., and Duffy, B.T., 2016, Toxicity of bed sediments from the Niagara River Area of Concern and tributaries, New York, to Chironomus dilutus and Hyalella azteca, 2014–15: U.S. Geological Survey Data Series 1016, XX p., http://dx.doi.org/10.3133/ds1016.