## 3 Results and Discussion
### Hydrochemical Conditions of the Studied Rivers
Conductivity varied significantly between rivers (\(p\leq\) 0.05), but remained below 360 \(\upmu\)S-cm\({}^{-1}\) across all sites, aligning with Class I water quality standards  
\begin{table}
\begin{tabular}{c|c|c|c|c|c|c} \hline
**Parameter** & **TP** & **NO2-N** & **NH4-N** & **Alkalinity** & **Total Hardness** & **Chlorides** \\
**River** & & mg\(\cdot\)L\({}^{-1}\) & & **mgCaCO\({}_{3}\)\(\cdot\)L\({}^{-1}\)** & **mgCO\({}_{3}\)\({}^{2-}\)\(\cdot\)L\({}^{-1}\)** & **mgCl\({}^{-1}\)\(\cdot\)L\({}^{-1}\)** \\ \hline \multirow{3}{*}{Molstowa} & 0.089 \(\pm\) 0.036 \({}^{\mathrm{a}}\) & 0.020 \(\pm\) 0.013 \({}^{\mathrm{b}}\) & 0.064 \(\pm\) 0.042 \({}^{\mathrm{b}}\) & 161.2 \(\pm\) 27.9 \({}^{\mathrm{a}}\) & 229.1 \(\pm\) 28.8 \({}^{\mathrm{a}}\) & 25.8 \(\pm\) 6.8 \({}^{\mathrm{a}}\) \\  & min-max & min-max & min-max & min-max & min-max & min-max \\  & 0.047-0.246 & 0.005-0.065 & 0.017-0.193 & 110.0–195.0 & 165.0–285.0 & 14.2–46.2 \\ \hline \multirow{3}{*}{Ukleja} & 0.092 \(\pm\) 0.059 \({}^{\mathrm{a}}\) & 0.015 \(\pm\) 0.007 \({}^{\mathrm{a}}\) & 0.049 \(\pm\) 0.041 \({}^{\mathrm{b}}\) & 181.7 \(\pm\) 22.5 \({}^{\mathrm{b}}\) & 225.5 \(\pm\) 41.0 \({}^{\mathrm{a}}\) & 33.7 \(\pm\) 9.7 \({}^{\mathrm{a}}\) \\  & min-max & min-max & min-max & min-max & min-max & min-max \\  & 0.021-0.297 & 0.005-0.032 & 0.007-0.299 & 111.5–230.0 & 87.5–276.0 & 14.2–56.8 \\ \hline \multirow{3}{*}{Gardomika} & 0.058 \(\pm\) 0.017 \({}^{\mathrm{a}}\) & 0.015 \(\pm\) 0.009 \({}^{\mathrm{a}}\) & 0.054 \(\pm\) 0.065 \({}^{\mathrm{a}}\) & 167.6 \(\pm\) 19.9 \({}^{\mathrm{a}}\) & 231.7 \(\pm\) 27.1 \({}^{\mathrm{a}}\) & 35.3 \(\pm\) 6.1 \({}^{\mathrm{b}}\) \\  & min-max & min-max & min-max & min-max & min-max & min-max \\  & 0.033–0.087 & 0.005–0.040 & 0.012-0.252 & 122.0–225.0 & 185.0–295.0 & 28.4–49.7 \\ \hline \multirow{3}{*}{Rekowa} & 0.083 \(\pm\) 0.025 \({}^{\mathrm{a}}\) & 0.012 \(\pm\) 0.012 \({}^{\mathrm{a}}\) & 0.064 \(\pm\) 0.029 \({}^{\mathrm{a}}\) & 161.0 \(\pm\) 27.8 \({}^{\mathrm{a}}\) & 227.7 \(\pm\) 27.8 \({}^{\mathrm{a}}\) & 25.8 \(\pm\) 5.9 \({}^{\mathrm{a}}\) \\  & min-max & min-max & min-max & min-max & min-max & min-max \\  & 0.059–0.144 & 0.003–0.049 & 0.020-0.173 & 109.0–179.5 & 192.5–275.0 & 17.8–39.1 \\ \hline \multirow{3}{*}{Piaskowa} & 0.081 \(\pm\) 0.041 \({}^{\mathrm{a}}\) & 0.013 \(\pm\) 0.005 \({}^{\mathrm{a}}\) & 0.077 \(\pm\) 0.052 \({}^{\mathrm{a}}\) & 185.7 \(\pm\) 14.6 \({}^{\mathrm{c}}\) & 238.5 \(\pm\) 31.9 \({}^{\mathrm{a}}\) & 32.1 \(\pm\) 13.7 \({}^{\mathrm{a}}\) \\  & min-max & min-max & min-max & min-max & min-max & min-max \\  & 0.025-0.198 & 0.004–0.023 & 0.02-0.166 & 170.0–230.0 & 120.0–257.5 & 17.8–95.9 \\ \hline \multirow{3}{*}{Lubieszowa} & 0.109 \(\pm\) 0.056 \({}^{\mathrm{a}}\) & 0.013 \(\pm\) 0.005 \({}^{\mathrm{a}}\) & 0.050 \(\pm\) 0.045 \({}^{\mathrm{a}}\) & 198.2 \(\pm\) 19.9 \({}^{\mathrm{c}}\) & 244.5 \(\pm\) 18.5 \({}^{\mathrm{b}}\) & 32.2 \(\pm\) 13.4 \({}^{\mathrm{a}}\) \\  & min-max & min-max & min-max & min-max & min-max & min-max \\  & min-max & min-max & min-max & min-max & min-max & min-max \\  & 0.065 \(\pm\) 0.038 \({}^{\mathrm{a}}\) & 0.014 \(\pm\) 0.008 \({}^{\mathrm{a}}\) & 0.075 \(\pm\) 0.046 \({(Tables 4 and 5) [17]. These values indicate low levels of mineralization, consistent with relatively unpolluted conditions. Total suspended solids (TSSs) exceeded the acceptable threshold of 25 mg\(\cdot\)L\({}^{-1}\) (Directive 2006/44/EC of the European Parliament and of the Council of 6 September 2006) in eight out of nine rivers (Tables 4 and 5). The most pronounced exceedances--more than double the limit--were recorded in the Molstowa, Piaskowa, Loznica, Brzeznicka-Wegorza, and Sapolna. Only the Gardominka had TSS concentrations that consistently met the standard for fish-supporting waters, with an average value of 18 mg\(\cdot\)L\({}^{-1}\).