Influence of dam reservoir on the water quality in a small upland river

The paper deals with the evaluation of functioning of the small dam reservoir localized in a loess agricultural catchment. During the survey, the reservoir had positive impact on water quality in supplying stream - the decrease of majority of the transported contaminants occurred, oxygen indicators were improved. Water flowing into the reservoir was characterized by insufficient quality. Extremely high phosphates concentration was recorded. Also CODCr, BOD5, NO2−, and Fe+ reached high values. In a consequence, a worsening of the stored water quality progressed. The excessive contaminants accumulation (including bottom sediments) and intensification of eutrophication processes greatly reduced the reservoir's usefulness for farming. Rational management and designing of a catchment (e.g. anti-erosion protection) should be one of the important elements at the process of water resources management.