The following parameters were determined in Lake Miedwie water: pH, suspended particulates, chlorophyll a, dissolved oxygen content, BOD5, CODCr, CODMn, orthophosphates, total phosphorus, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, organic nitrogen, and total nitrogen as well as parameters important for evaluation of the mineralisation level, i.e., chlorides, sulphates, carbonates, hydrocarbonates, calcium, magnesium, and electric conductivity. The results allowed to assess the Miedwie water quality. The good oxygen conditions found in the lake, an average nutrient content, and the high water transparency allow to classify the lake as a mesotrophic one. The constant supply of nutrients and organic matter from the entire catchment result in permanent nutrient and organic loads in the lake. All the mineralisation indices evidenced an average mineralisation level, typical of the Western Pomeranian surface waters, and ranged within limits typical of the water quality class 1.

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