We examined microplastic concentrations, size distributions and polymer types in surface waters of a northern European dimictic lake. Two sampling methods, a pump sieving water onto filters with different pore sizes (20, 100 and 300 μm), and a common manta trawl (333 μm), were utilized to sample surface water from 12 sites at the vicinity of potential sources for microplastic emissions. The number and polymer types of microplastics in the samples were determined with optical microscopy and μFTIR spectroscopy. The average concentrations were 0.27 ± 0.18 (mean ± standard deviation) microplastics m in manta trawled samples and 1.8 ± 2.3 (>300 μm), 12 ± 17 (100-300 μm) and 155 ± 73 (20-100 μm) microplastics m in pump filtered samples. The majority (64%) of the identified microplastics (n = 168) were fibers and the rest were fragments. Materials were identified as polymers commonly used in consumer products, such as polyethylene, polypropylene and polyethylene terephthalate. Microplastic concentrations were high near the discharge pipe of a wastewater treatment plant, harbors and snow dumping site. This article is protected by copyright. All rights reserved.