## 3 Results  
### Hydrometeorological Conditions in the Catchment of the River Swierszcz  
As stated in the previous section, the quality tests of various types of water from the catchment of the River Swierszcz were carried out in the years 2021-2022. In order to determine the quantitative background for the waters tested, we also analysed the meteorological (temperatures and precipitation) and hydrological (water flow and groundwater levels) conditions in the catchment of the River Swierszcz recorded for the same period (Figure 7).  
Since groundwater and surface water reserves are strictly dependent on the temperatures and precipitation levels in a given area over a longer period, meteorological data from the years 2021-2022 were compared with data for two decades collected between 2001 and 2020, as reported in a paper by [PERSON] et al. [31]. Hydrological data (water flows of the River Swierszcz and groundwater table levels), on the other hand, were compared with data for the years 2012-2020 contained in the reports of the R  
\begin{table}
\begin{tabular}{l c c c c c c c c c} \hline \hline \multirow{2}{*}{**Test Parameters**} & \multirow{2}{*}{**Unit**} & \multirow{2}{*}{**Quality Standards for**} & \multicolumn{3}{c}{**Surface Water Purity**} & \multicolumn{3}{c}{**Groundwater Purity Classes [32]**} \\ \cline{3-10}  & & & **Dinking Water**[36] & **I** & **II** & **I** & **II** & **III** & **IV** & **V** \\ \hline \multicolumn{10}{c}{Microbiological parameters} \\ Total microbial count at 36 \({}^{\circ}\)C & cfu/mL & 100 & - & - & - & - & - & - & - & - \\ _Escherichia coli_ & cfu/100 mL & 0 & - & - & - & - & - & - & - \\ Intestinal meteorococci & cfu/100 mL & 0 & - & - & - & - & - & - & - & - \\ _Pseudomonas aeruginosa_ & cfu/100 mL & 0 & - & - & - & - & - & - & - & - \\ \hline Turbidity & \multicolumn{6}{c}{Physicochemical parameters} \\ Colour & mTU & 1 & - & - & - & - & - & - & - & - \\ pH & \multicolumn{6}{c}{6.5-9.5} & 7.5-8.2 & 7.3-8.2 & \multicolumn{6}{c}{6.5-9.5} \\ Specific conductance at 25 \({}^{\circ}\)C & \(\mu\)S/cm & 2500 & \(\leq\)364 & \(\leq\)544 & 700 & 2500 & 2500 & 3000 & \(>\)3000 \\ Ammonium ion \({}^{\star}\) & mg/L & 0.5 & \(<\)0.477 & \(\leq\)0.545 & 0.5 & 1 & 1.5 & 3 & 3.0 \\ Nitrates \({}^{\star}\) & mg/L & 50 & \(\leq\)5.752 & \(\leq\)8.407 & 10 & 25 & 50 & 100 & \(>\)100 \\ Nitrites \({}^{\star}\) & mg/L & 0.5 & \(\leq\)0.033 & \(\leq\)0.089 & 0.03 & 0.5 & 0.5 & 1 & \(>\)10 \\ Manganese & mg/L & 0.05 & - & - & 0.05 & 0.4 & 1 & 1 & \(>\)10 \\ Total iron & mg/L & 0.2 & - & - & 0.2 & 1 & 5 & 10 & \(<\)10 \\ Chlorides & mg/L & 250 & \(\leq\)13.3 & \(\leq\)158.7 & 60 & 150 & 250 & 500 & \(>\)500 \\ Total hardness CaCO3 & mg/L & 60–500 & \(\leq\)203 & \(\leq\)236 & - & - & - & - & - \\ \hline \hline \end{tabular}  
* Since the regulation of the Polish Minister of Infrastructure [37] lists the following forms of nitrogen: N-NH\({}_{4}\), N-NO\({}_{3}\) and N-NO\({}_{2}\); the concentrations of nitrogen in the form of ammonium ion, nitrates and nitrites in surface waters was calculated using the following equations: NH\({}_{4}\) = N-NH\({}_{4}\)/0.776, NO\({}_{3}\) = N-NO\({}_{3}\)/0.226 and NO\({}_{2}\) = N-NO\({}_{2}\)/0.304.  
\end{table}
Table 2: Drinking water quality standards and purity classes for surface water and groundwater stipulated in Polish legal acts [32; 36; 37].