To investigate the effects of imidacloprid on natural stream communities under controlled conditions, experimental streams were dosed with imidacloprid at concentrations ranging from 0.061 to 220 micrograms per liter (µg/L) for a period of 10 days. Natural stream macroinvertebrate communities were obtained from the Cache La Poudre River (Larimer County, CO) by colonizing trays full of large gravel for 75 days. The trays were added to laboratory experimental streams (mesocosms) at the USGS Fort Collins Science Center in Fort Collins, CO. At the end of 10 days, invertebrate abundance metrics were analyzed in relation to measured imidacloprid concentrations in water from the experimental streams. Declines in total abundance and Ephemeroptera, Plecoptera and Tricoptera taxa abundance were observed in the mesocosm communities at concentrations of 1 µg/L and above, and one sensitive species, Baetis tricaudatus, was affected at concentrations as low as 0.060 µg/L.

Neonicotinoids, a widely used class of insecticide, have been found in surface waters globally. They pose a risk to non-target species found in aquatic environments such as aquatic macroinvertebrates. To better understand the effects of the neonicotinoids imidacloprid, clothianidin and their mixtures on aquatic communities we ran a 30 day mesocosm test. Rock trays were colonized with natural benthic communities in the Cache La Poudre River, located in the mountains of Northern Colorado, and relocated to a laboratory experimental stream setting. In total there were 33 experimental streams: 3 controls and 30 treatments consisting of both single compound and binary compound exposures with 5 treatment levels for each exposure series. Water quality and chemistry samples were collected throughout the experiment. Larval invertebrates remaining in each experimental stream at the end of the experiment were collected, enumerated and identified to the lowest taxonomic unit practical, typically genus or species. Emergent insects were collected each day of the experiment and identified to lowest taxonomic unit. Chlorophyll a was measured in each experimental stream 3 times throughout the 30 day experiment.

Neonicotinoids, a widely used class of insecticide, have been found in surface waters globally. They pose a risk to non-target species found in aquatic environments such as aquatic macroinvertebrates. To better understand the effects of the neonicotinoids imidacloprid, clothianidin and their mixtures on aquatic communities we ran a 30 day mesocosm test. Rock trays were colonized with natural benthic communities in the Cache La Poudre River, located in the mountains of Northern Colorado, and relocated to a laboratory experimental stream setting. In total there were 33 experimental streams: 3 controls and 30 treatments consisting of both single compound and binary compound exposures with 5 treatment levels for each exposure series. Water quality and chemistry samples were collected throughout the experiment. Larval invertebrates remaining in each experimental stream at the end of the experiment were collected, enumerated and identified to the lowest taxonomic unit practical, typically genus or species. Emergent insects were collected each day of the experiment and identified to lowest taxonomic unit. Chlorophyll a was measured in each experimental stream 3 times throughout the 30 day experiment.

A data release containing information on benthic macroinvertebrate communities and sediment toxicity in the Eighteenmile Creek Area of Concern and a nearby reference area at Oak Orchard Creek. Bed sediments were collected during summer 2021 at 8 sites on Eighteenmile Creek and at 6 sites on Oak Orchard Creek using a petite Ponar dredge for macroinvertebrate identification and sediment toxicity testing. Macroinvertebrates were identified to the lowest practical taxonomic resolution and used to calculate metrics of biological integrity following standard New York State Department of Environmental Conservation procedures. 10-day sediment toxicity tests were conducted using two test species, Chironomus dilutus and Hyalella azteca, following USEPA test methods 100.2 and 100.1, respectively. In situ habitat measurements and sediment samples for determination of grain size distribution and total organic carbon concentration were also taken at the time of sample collection at all sites. The data release has four separate tables: one containing site locations and habitat information, one containing the results of sediment toxicity tests, one containing macroinvertebrate identifications, and one containing standard New York State Department of Environmental Conservation metrics of macroinvertebrate community integrity calculated from the macroinvertebrate identifications.

A data release containing information on benthic macroinvertebrate communities and sediment toxicity in the Eighteenmile Creek Area of Concern and a nearby reference area at Oak Orchard Creek. Bed sediments were collected during summer 2021 at 8 sites on Eighteenmile Creek and at 6 sites on Oak Orchard Creek using a petite Ponar dredge for macroinvertebrate identification and sediment toxicity testing. Macroinvertebrates were identified to the lowest practical taxonomic resolution and used to calculate metrics of biological integrity following standard New York State Department of Environmental Conservation procedures. 10-day sediment toxicity tests were conducted using two test species, Chironomus dilutus and Hyalella azteca, following USEPA test methods 100.2 and 100.1, respectively. In situ habitat measurements and sediment samples for determination of grain size distribution and total organic carbon concentration were also taken at the time of sample collection at all sites. The data release has four separate tables: one containing site locations and habitat information, one containing the results of sediment toxicity tests, one containing macroinvertebrate identifications, and one containing standard New York State Department of Environmental Conservation metrics of macroinvertebrate community integrity calculated from the macroinvertebrate identifications.

Zooplankton samples were collected in the summer/fall of 2022 and 2023 at multiple sites in the Sacramento River, Yolo Bypass, and Cache Slough Region of California and analyzed for a suite of 160 current-use pesticides and pesticide degradates by the U.S. Geological Survey Organic Chemistry Research Laboratory. In 2022 samples were collected at two sites in the Bypass and at a comparison site on the Sacramento River from early August to mid-October. In 2023 zooplankton samples were collected at one site upstream of the Yolo Bypass in Northern California, four sites within the Bypass, one site downstream of the Bypass in the Cache Slough region, and at a comparison site on the Sacramento River from late July through early October. Samples were collected every two weeks by towing a 150-micron conical plankton net for 5 minutes by boat at each site. In the laboratory, zooplankton samples were filtered through a 63-micrometer sieve to separate the zooplankton and vegetation/detritus from the water. Large sticks, twigs, rocks, and leaves were rinsed with organic free water into the sieve and then discarded. The remaining mass in the sieve was transferred into 50 milliliter plastic centrifuge tubes, frozen overnight at -20 degrees Celsius, dehydrated completely using a freeze dryer, and then stored at -20 degrees Celsius. Immediately prior to analysis, each freeze-dried sample was homogenized and sub-sampled to a targeted final weight of 0.5 grams. Sub-samples were further homogenized with magnesium sulfate and extracted with acetonitrile at 100 degrees Celsius using an EDGE Automated Extraction System following procedures outlined in Black and others, (2023). Extracts were cleaned up using activated carbon and evaporated to 200 microliters in acetonitrile. Each sample had internal standards added and was analyzed by gas chromatography-tandem mass spectrometry for 27 pesticides and by liquid chromatography tandem mass spectrometry for 133 pesticides following methods described in Gross and others, (2024). A total of 15 pesticides were detected in the 18 zooplankton samples collected in 2022, and 16 of the samples contained multiple pesticides (up to 9 per sample). The most frequently detected compounds in 2022 were azoxystrobin, bifenthrin, fluridone, and p,p’-DDE. A total of 25 pesticides were detected in the 55 zooplankton samples collected in 2023, and 50 of the samples contained multiple pesticides (up to 16 per sample). The most frequently detected compounds in 2023 were azoxystrobin, bifenthrin, and p,p’-DDE.

These data were used for an analysis as part of a long-term project monitoring the biological communities, habitat, and water quality of the Fountain Creek Basin. Biology, habitat, and water quality data have been collected at 10 sites starting in 2003. These data include annual samples of aquatic invertebrate communities, fish communities, water quality, and quantitative riverine habitat collected from 2003-2016. These data will provide insight into trends in biological communities from 2003-2016 and relationships between biological communities and abiotic variables (antecedent streamflow, physical habitat, and water quality). This USGS data release contains all the input and output data and files necessary to reproduce results of the report describing an analysis of ecological trends from 2003-2016 in the Fountain Creek Basin, Colorado, USA (https://doi.org/10.3133/sir20175162). Data preparation of these data files is fully described in the report mentioned previously. These data are outputs from the two-step trend analysis and provide the statistical measures of trend significance, potential drivers of trends, and the change in each biological metric over this trend period (2003-2016).

These data were used for an analysis as part of a long-term project monitoring the biological communities, habitat, and water quality of the Fountain Creek Basin. Biology, habitat, and water quality data have been collected at 10 sites starting in 2003. These data include annual samples of aquatic invertebrate communities, fish communities, water quality, and quantitative riverine habitat collected from 2003-2016. These data will provide insight into trends in biological communities from 2003-2016 and relationships between biological communities and abiotic variables (antecedent streamflow, physical habitat, and water quality). This USGS data release contains all the input and output data and files necessary to reproduce results of the report describing an analysis of ecological trends from 2003-2016 in the Fountain Creek Basin, Colorado, USA (https://doi.org/10.3133/sir20175162). Data preparation of these data files is fully described in the report mentioned previously. These data are outputs from the two-step trend analysis and provide the statistical measures of trend significance, potential drivers of trends, and the change in each biological metric over this trend period (2003-2016).

This dataset contains estimated time-weighted average water concentrations of pesticides sampled using polar organic chemical integrative sampler (POCIS) samples.

These data from Evaluation and Review of Ecology-Focused Stream Studies to Support Cooperative Monitoring, Fountain Creek Basin, Colorado were used to describe temporal trends in invertebrate communities in the basin. Invertebrate data were collected at U.S. Geological Survey (USGS) sites between 1985 and 2022. Datasets include invertebrate frequency of occurrence, invertebrate tolerance index values, invertebrate multi-metric index, New Zealand mudsnial counts, and list of invertebrate species collected.