Illegal waste deposition in places unadapted for this purpose poses a hazard to the natural environment. Each year over 10 000 illegal dumping sites are liquidated in Poland. The areas where illegal landfills occur are most frequently situated in the vicinity of waste management plants, wastelands, roadsides, byways or unfenced private plots (particularly on the city outskirts), forests and water courses. Despite of the changes introduced in recent years in the system of municipal solid waste management in Poland, which in the first place aimed to prevent formation of illegal dumps, such places still arise causing pollutant emission into the atmosphere. The aim of the paper was conducting an analysis of the existing illegal dumping sites in Krosno commune (Podkarpackie voivodship). The investigations were conducted along the selected stretches of the Wisłok and Lubatówka rivers. The analyses were carried out in three measurement series during the period from March to October 2014. As results from the analyses, new illegal dumping sites arise all the time in the water courses in Krosno city and a majority of them can be easily identified in this area. Glass and plastics have the biggest share in the morphological composition of the waste deposited on ...