This dataset describes the total concentration (Microplastics per Liter - MPL) of microplastics in surface water from eighteen distinct inland lakes in Minnesota. It also includes individual microplastic characteristics such as the longest measured dimension, width perpendicular to the longest dimension, color, morphology, length-to-width ratio, and composition. Spatial land use data, U.S. Census variables, and socioeconomic information for each lake's watershed are also provided. Surface water samples were collected using 100 micrometer net tows from May 2023 through July 2023. Sampling and analysis methods are detailed in the Processing Steps section of the metadata. This dataset is part of an ongoing collaborative effort between the Minnesota Pollution Control Agency, University of Minnesota-Duluth, and the U.S. Geological Survey. Future versions of this data release are planned to include total concentration (Microplastics per Liter - MPL) of microplastics, and individual microplastic characteristics (as defined above) in sediment from twenty-seven locations across eighteen inland Minnesota lakes, in addition to surface water and sediment from twenty-two major river basin locations in Minnesota.