This dataset describes the concentration and morphology of microplastics in the St. Croix National Scenic Riverway and Mississippi National River and Recreation Area, Wisconsin and Minnesota. Samples were collected during baseflow conditions at eight locations during the week of August 3-7, 2015. Four types of samples were collected: water surface, streambed sediment, smallmouth bass (Micropterus dolomieu), and threeridge mussels (Amblema plicata). Water surface samples were collected at all eight sites; other sample types were collected at only a subset of sites.

This dataset describes the quantity and morphology of microplastics in water, sediment, fish, and mussel samples from the Delaware River and select tributaries, including portions of the Upper Delaware Scenic & Recreational River, Middle Delaware National Scenic River, Delaware Water Gap National Recreation Area, and Lower Delaware Scenic & Recreational River. Water and sediment samples were collected at nine locations, from Callicoon, New York, at the upstream end, to Burlington, New Jersey, at the downstream end. Smallmouth bass (Micropterus dolomieu), white sucker (Catostomus commersonii), and eastern elliptio (Elliptio complanata) were sampled at a subset of locations to assess biological uptake of microplastics. Sampling and analysis methods are described in the Processing Steps section of the metadata. Samples were collected July 2018 - March 2019.

This dataset describes the quantity and morphology of microplastics in water, sediment, fish, and mussel samples from the Delaware River and select tributaries, including portions of the Upper Delaware Scenic & Recreational River, Middle Delaware National Scenic River, Delaware Water Gap National Recreation Area, and Lower Delaware Scenic & Recreational River. Water and sediment samples were collected at nine locations, from Callicoon, New York, at the upstream end, to Burlington, New Jersey, at the downstream end. Smallmouth bass (Micropterus dolomieu), white sucker (Catostomus commersonii), and eastern elliptio (Elliptio complanata) were sampled at a subset of locations to assess biological uptake of microplastics. Sampling and analysis methods are described in the Processing Steps section of the metadata. Samples were collected July 2018 - March 2019.

This dataset describes the quantity and morphology of floating microplastics in 29 Great Lakes tributaries in 6 states. Samples were collected in spring 2014 – spring 2015. Each tributary was sampled three to four times, capturing low-flow and runoff-event conditions. Sampling and analysis methods are described in the .xml metadata file. These data are interpreted in a journal article (cite journal article).

This dataset describes the quantity and morphology of floating microplastics in 29 Great Lakes tributaries in 6 states. Samples were collected in spring 2014 – spring 2015. Each tributary was sampled three to four times, capturing low-flow and runoff-event conditions. Sampling and analysis methods are described in the .xml metadata file. These data are interpreted in a journal article (cite journal article).

This dataset describes the quantity and morphology of microplastics in water, surficial sediment, sediment core, fish, and shellfish samples from Lake Mead National Recreation Area (Nevada/Arizona). Water and surficial sediment samples were collected once at 9 locations. A sediment core (33 cm long) was extracted from Las Vegas Bay to assess changes in microplastic deposition over time. Striped bass (Morone saxatilis), common carp (Cyprinus carpio), quagga mussels (Dreissena bugensis), and Asian clams (Corbicula fluminea) were sampled at a subset of locations to assess biological uptake of microplastics. Sampling and analysis methods are described in the Processing Steps section of the metadata. All samples were collected in March 2017 except the sediment core, which was collected in March 2018.

This dataset describes the quantity and morphology of microplastics in water, surficial sediment, sediment core, fish, and shellfish samples from Lake Mead National Recreation Area (Nevada/Arizona). Water and surficial sediment samples were collected once at 9 locations. A sediment core (33 cm long) was extracted from Las Vegas Bay to assess changes in microplastic deposition over time. Striped bass (Morone saxatilis), common carp (Cyprinus carpio), quagga mussels (Dreissena bugensis), and Asian clams (Corbicula fluminea) were sampled at a subset of locations to assess biological uptake of microplastics. Sampling and analysis methods are described in the Processing Steps section of the metadata. All samples were collected in March 2017 except the sediment core, which was collected in March 2018.

This dataset describes the quantity, morphology, concentration and polymer identity of microplastics in surficial benthic sediment of Lake Michigan and Lake Erie. Lake Michigan sediment samples were collected at 20 locations in September, 2013 and Lake Erie sediment samples were collected at 12 locations in September, 2014 while on-board the R.V. Lake Guardian. Sampling and analysis methods are described in the Processing Steps section of the metadata.

This dataset describes the quantity, morphology, concentration and polymer identity of microplastics in surficial benthic sediment of Lake Michigan and Lake Erie. Lake Michigan sediment samples were collected at 20 locations in September, 2013 and Lake Erie sediment samples were collected at 12 locations in September, 2014 while on-board the R.V. Lake Guardian. Sampling and analysis methods are described in the Processing Steps section of the metadata.

This dataset describes the quantity, morphology, and polymer identity of microplastics in the water column and surficial sediments of Milwaukee-Area streams, the Milwaukee Harbor, and Lake Michigan (Wisconsin). Water samples were collected at 10 locations, 2-4 times each, from May to September, 2016. At the 4 shallowest locations, water was collected only at the water surface. At the remaining 6 locations, water was collected at the water surface and at 1-4 depths below the surface. Sediment samples were collected once, in June 2016, at a subset of 9 locations. Sampling and analysis methods are described in the Processing Steps section of the metadata. These data are interpreted in the following journal article: Lenaker, P. L., Baldwin, A. K., Corsi, S. R., Mason, S. A., Reneau, P. C., & Scott, J. W. (2019). Vertical Distribution of Microplastics in the Water Column and Surficial Sediment from the Milwaukee River Basin to Lake Michigan. Environmental Science & Technology, 53(21), 12227–12237, https://doi.org/10.1021/acs.est.9b03850.