Studies of surface waters were carried out in a suburban catchment of the Sudół Dominikański stream where a small storage reservoir is to be built. Water for analyses was ampled from the gauging section situated on the main watercourse immediately below the dam of the projected reservoir, at 14 dates in the period of July 2005 to February 2007. Additionally, at one date the quality of water was examined at six other points located on the main watercourse and its tributary. Standard methods were used to determine 18 physicochemical properties, including 16 quality indices, of water at each measuring-and-control point. The results revealed that the degradation of water is far advanced in the dam section of the planned reservoir. The water contains high concentrations of phosphates and of ammonium and nitrite nitrogen forms. The inflow of treated sewage from the local treatment plant constitutes the main source of pollution. The current level of water pollution in the stream poses a threat of eutrophication to the future reservoir.

The identification and evaluation of the non-point anthropogenic influences on the quality of water in the Struga Dormowska stream catchment was made by using indicators characterising municipal economy, agriculture and forestry, and industry. The quality of water in the catchment was assessed on the basis of observations and measurements made from May to November 2007. It was found that the pressure on the water resources in the Struga Dormowska stream catchment is highest for agriculture, while municipal economy and industry exert medium pressure. Despite the high consumption of fertilisers and intensive livestock breeding, the waters in the catchment usually meet the standards for the 1st, 2nd and 3rd quality class. This suggests that the waters are protected against pollution with biogenic compounds, probably due to the high proportion of forests and protected lands in the catchment. The high values of COD result from insufficiently strict waste-water management in the catchment.

Research carried out in the hydrological years 1997–2002 investigated the concentration of nitrates in drainage waters from three sites differing in physiographic, climatic and soil conditions. The compounds were determined one or two times per month in the period with outflows. Chemical analyses were performed using spectrophotometric method with 2,6-dimethylphenol. It was found that the drainage waters contained high amounts of nitrates: the mean ranged from 67.7 to 105.0 mg NO₃ · dm^–3, and the maximum values exceeded 240 mg NO₃ · dm^–3 and usually appeared in early spring. The mean concentration of nitrates constituted 36 to 45% of the maximum value, so the range of ratios between the mean and the maximum was narrow. If such a result is confirmed in further studies involving a larger number of measuring series, it would be possible to suggest using the mean value for the description of an experimental series. This is a measure that well describes a sample and is independent of incidental single values diverging from the others in the series.

Sewage sludges mixed with peat at a dry weight ratio of 1 : 1 were kept in PCV containers, and water losses were periodically made up during storage. The original materials and the materials stored for 1 month and 36 months were examined for pH, electrolytic conductivity, and the levels of dry matter, organic carbon, humus compound fractions, nitrogen and heavy metals (Zn, Pb, Cu, Cd). The results were compared with those for farmyard manure and peat. It was found that the dry matter content, pH value and electrolytic conductivity of the sludge-peat mixtures increased after 36-month storage, while the organic carbon content and, to a lesser degree, the total nitrogen content tended to decrease with time. As a result of the transformations of organic matter occurring in the mixtures, the amounts of soluble organic compounds systematically decreased. The proportion of carbon extracted with sodium pyrophosphate and sodium base was lower than 20% of the total organic carbon content whereas that of nonhydrolysing carbon exceeded 80%. The humus compounds in the mixtures contained more humic acids carbon than fulvic acids carbon. The level of the mobile forms of heavy metals in the sewage sludge-peat mixtures was low, which indicates that these elements occurred in the form of less bioavailable compounds.

The relationship between the Na⁺, K⁺, Ca²⁺ and Mg²⁺ concentration in water extracts from composts made of anaerobic sewage sludge from the sugar industry and the electric conductivity of the extracts was investigated for the purposes of estimating the maturity of composts. The conductivity values proved to be correlated with the concentration of the cations. The determination coefficients were statistically significant (p = 0.05) for composts with an addition of structure-forming materials (straw, farmyard manure). This means that the measurement of conductivity can be used to estimate the degree of mineralisation of composted materials.