The study presents an analysis of changeability and trends for nitrogen compounds in the catchment of the Strzegomka River in the years 2000–2014. Tests were conducted in the cross-section above the Dobromierz Reservoir, which provides drinking water for the inhabitants of Świebodzice. The conducted analyses demonstrated that nitrogen compounds concentrations were characterised by high changeability. The main problem was the high concentration of nitrate nitrogen, which amounted, on the average, to 5.5 mg N-NO3 · dm–3 in the research period. They contributed to the poor quality of the water in the Strzegomka River, and, together with high total nitrogen content, to its eutrophication. The lowest concentrations of nitrogen compounds were noted in the summer (total and nitrate nitrogen) and autumn (Kjeldahl and ammonium nitrogen), while the highest concentrations of all forms occurred in winter. The concentrations of total, nitrate and ammonium nitrogen in the analysed cross-section demonstrate a statistically confirmed decreasing tendency, while no significant trend was observed for Kjeldahl nitrogen.