## 4 Discussion
5 \({}^{\circ}\)C and during the winter, when the air temperatures are low, the water temperature sometimes drops to 0 \({}^{\circ}\)C, which means that it partially freezes. This results in water resources being particularly low in winter [23]. With regard to the fact that water used for the production of artificial snow is stored in a technical reservoir prior to its use, the majority of bacteria contaminating the water will remain in the reservoir sediment [24], while its chemical composition might affect the waterin the Remiaszow stream, mostly during the spring snow-melt period, when water from the artificial snow will reach the stream. The land cover changes, caused by the construction of the ski slope, i.e., among other things--tree cutting, soil cover violation and destruction of meadow vegetation leading to increased leaching of K\({}^{+}\), Mg\({}^{2+}\), NO\({}_{3}\)\({}^{-}\) and SO\({}_{4}\)\({}^{2-}\) ions, together with bacteria, i.e., total coliforms, total _E. coli_, fecal _E. coli_ and mesophilic bacteria. This caused an increase in the concentration of these parameters in the water of the Remiaszow stream during the construction works. Such phenomenon of increased leaching due to changes in the land cover and disturbance of the soil cover has often been described in the literature. Many authors [25; 26; 27; 28] indicate that the removal of vegetation, most importantly trees, decreases nutrient assimilation, particularly NO\({}_{3}\)\({}^{-}\). The observed increase in the concentration of cations: Ca\({}^{2+}\), Mg\({}^{2+}\), K\({}^{+}\) in stream waters is also associated with the disturbance of the soil cover and the resulting increased erosion, which affects faster leaching of these compounds from the catchment [25; 27; 29; 30; 31; 32]. However, over time and with the recovery of the plant cover, the ion concentrations drop to the level recorded before the land cover change [33; 34]. Similarly, in studies conducted by [PERSON] et al. [27], the chemical composition of the water had already returned to the condition recorded before the forest clearance after approximately one year after the initiation of the harvest. It was also observed that the SO\({}_{4}\)\({}^{2-}\) concentrations still grow, while the level of the remaining ions decreases. Similar results were obtained by [PERSON] et al. [33], who associated the results with acidification and sulfate adsorption processes in the soil. Construction of the new ski slope and, in particular, the production of artificial snow made of water from the river Bialka, resulted in increased values of pH, EC, TDS and the concentrations of Ca\({}^{2+}\), Mg\({}^{2+}\) and HCO\({}_{3}\)\({}^{-}\) in the water of the Remiaszow stream. This is caused by the supply of melt water from artificial snow, which is much more mineralized than natural atmospheric precipitation. On the other hand, the concentrations of Na\({}^{+}\), K\({}^{+}\), Cl\({}^{-}\) and NO\({}_{3}\)\({}^{-}\) returned to the ones observed before the construction of the slope and violation of the plant-soil cover. This may evidence their retention in the catchment by the reviving vegetation on the mentioned slope. The disturbance of the soil cover also increases the amount of suspension in the water, resulting in elevated numbers of bacterial indicators of poor water quality. It was demonstrated by numerous authors that the number of bacteria in water is significantly associated with the amount of suspended solids [35; 36]. Another factor affecting the increased number of bacteria in water can be related to sheep grazing on the ski slope. For instance, [PERSON] et al. [37] demonstrated that on the slopes where sheep are grazed, increased leaching of coliform bacteria occurs, whereas this effect was not observed in the case of nitrogen compounds. Additionally, the fresh feces of grazing animals is one of the two main non-human sources of waterborne fecal indicator microorganisms [38].