Impacts of antropogenic activities on the biogenic pollution of water is discussed on an example of physical and chemical parameters of water in East Lithuanian streams such as the Dubinga, Galba, Luknelė, Pavarklas, Peršokšna, Sakiena, Tola, Žvėrupis. Antropogenic activities of agricultural subjects and their effects on biogenic water pollution was determined, and causal relationships were analyzed according to separate spheres of agricultural activities – agriculture and cattle-breeding. The aim of the work was to determine the effect of agricultural activities on the pollution of biogenic matters in streams. The study revealed a correlation between water quality in streams and agricultural activities performed on the banks of these streams (area of agricultural land, number of cattle and poultry). The level of water pollution depended on the percentage of agricultural land in the catchments of streams and on the intensity of agricultural activities. Rivers in the catchments of which agricultural land exceeded 50% of the general area were most severely polluted. An analysis according to Spearman showed a close correlation between the content of pollutants in water and the percentage of the area of agricultural land in the catchments of these rivers, which was very strong for total nitrogen (r = 0.875) and strong for total phosphorus (r = 0.766).

Keywords: biogenic pollution of water, load of agricultural land, animal unit equivalents