The purpose of this paper was to determine changes in loads of N-NH₄⁺, S-SO₄², P-PO₄^3-, N-NO₃^-, P_og, Cl^-, Ca²⁺, Mg²⁺, and their origin in waters outflowing from Supraśl catchment. Research was carried out in the period from 2001 to 2009 in three measurement points located around Gródek, Nowodworce and Dzikie. Obtained values of specific load were raging for: N-NH₄⁺ 0.051÷2.094 kg N-NH₄⁺·ha^-1·year^-1, S-SO₄^2- 16.50÷30.00 kg S-SO₄^2-·ha^-1·year^-1, P-PO₄^3- 0.17÷0.45 kg P-PO₄³·ha^-1·year^-1, P_og 0.44÷0.78 kg P·ha^-1·year-1, Cl^- 14.58÷26.80 kg Cl^-·ha^-1·year^-1, Ca²⁺ 68.2÷77.1 kg Ca²⁺·ha^-1·year^-1, Mg²⁺ 9.57÷12.29 kg Mg²⁺·ha^-1·year^-1. In addition, linear Pearson correlation coefficients were calculated between specific loads of individual components and fertilization form in each measuring point. There were obtained statistically significant correlations between NPK fertilization and specific loads of N-NH₄⁺, P_og, Cl^-, Ca²⁺ i Mg²⁺ and between manure fertilization and S-SO₄^2-, Ca²⁺ i Mg²⁺.