There are several reasons for the decline of the olm population. The key threats are all types of pollution found in the Karst terrain (such as intense agriculture, industrial and urban waste and emissions, urbanisation, unauthorised landfills) in the influential area of underwater and sinkhole flows. These types of pollution deteriorate the quality of the habitat and shrink it as a consequence. Toxic and dangerous substances which pose a particular threat to the habitat are artificial fertilisers, pesticides, heavy metals, and other pollutants. Another negative factor can also be the irresponsible manner of using groundwater for industrial and agricultural purposes which reduce the groundwater reserves.