A comparison between the water quality of the main tributaries to three submontane dam reservoirs and the sediment quality in those reservoirs

Nutrients, pH, and organic matter were determined in water samples collected from the Raba River above Dobczyce Reservoir (meso-eutrophic), from the Dunajec River above Czorsztyn Reservoir (mesotrophic), and Rożnów Reservoir (eutrophic), and in the bottom sediments of the reservoirs. The river waters were alkaline (pH 7.2-9.2). In the Raba River and Dunajec River, the ranges of nutrients and organic matter contents were similar (without significant differences) (in mg dm^-3; N-NO₃ 0.5-2.5, N-NH₄ 0.2-2.0, N-NO₂ 0.004-0.040, N-tot 1.1-5.6, PO₄ 0.02-0.58, P-tot 0.03-1.9, while BOD₅ 1.6-9.9 mg dm^-3 O₂, COD 2.1-30.4 mg dm^-3 O₂). The pH of reservoir sediments was from neutral to slightly alkaline (6.9-7.6). The sediments were mineral and were characterized by a low amount of nutrients (N-tot 0.04-0.36%, P-tot 0.007-0.185%) and organic matter (expressed as LOI 3.0-10.6%, TOC 0.9-3.3%). Nutrient (except P-tot) and organic matter contents in the sediments of three reservoirs were similar (without significant differences) and did not reflect the trophic state of the reservoirs.