## 2 Materials and Methods
### Data Analysis  
The data were then analyzed from an environmental, social, and economic perspective, taking into account the following aspects:  
* Assessment of the physicochemical status of elements of water was conducted based on the regulation in force in Poland on the classification of ecological status [34] and implementing the assumptions resulting from the Water Framework Directive concerning the monitoring of surface water bodies [35]. The assessment was carried out for nine physicochemical parameters. For the river type 21, i.e., great lowland river [36], classification details are presented in Table 2. After the evaluation, the results were transformed, i.e., class I--1 point, class II--2 points, class III--3 points, and then the average physicochemical status for each parameter was calculated using the following scale: 1.00-1.66 points--class I, 1.67-2.33 points--class II, and 2.34-3.00 points--class III. The compliance with the standards [34] was also assessed concerning the limit values of the state of the analyzed physicochemical parameters, expressed as the quotient of the average concentration of a given parameter from the research period to the limit value specified in the regulation mentioned above, and then the results were classified according to the following scale: 0.00-1.00 points--very good quality of the physicochemical parameter, 1.01-2.00 points--good quality of the parameter, 2.01-3.00 points--moderate quality of the parameter, 3.01-4.00 points--poor quality of the parameter, and >4.00 points--bad quality of the parameter. * Determination of the trophic status of water based on the Carlson index (TSI\({}_{\rm P}\)) [37; 38; 39; 40] and the Trophic Level Index (TLI) [41; 42; 43] was conducted based on the average concentration of total phosphorus (TP) and, in the case of TLI, total nitrogen (TN = NH\({}_{4}\)-N + NO\({}_{3}\)-N + NO\({}_{2}\)-N) from the analyzed research period (TP and TN in \(\upmu\)g/L) for each of the points was taken into account, using the following Formulas (1)-(4) [37; 41]: \[{\rm TSI_{P}=14.42\ log\ (TP)+4.15}\] (1) \[{\rm TLI=0.50\ (TL_{N}+TL_{P})}\] (2) \begin{table}
\begin{tabular}{c c c c} \hline No. & Parameter & Name of the Method & Measurement Range \\ \hline
1. & pH & Potentiometric method & 0.00–14.00 \\ \hline
2. & Electrical conductivity (EC) & Conductometric method & 0.1–2000 \(\upmu\)S/cm \\ \hline
3. & Temperature of water (Temp.) & Temperature sensor (in situ tests) & \(-\)50.0–199.9 \({}^{\circ}\)C \\ \hline
4. & Turbidity (Turb.) & Nephelometric method & 0.1–1000 NTU \\ \hline
5. & Ammonium nitrogen (NH\({}_{4}\)-N) & & 0.001–1000 mg/L \\ \hline
6. & Nitrate nitrogen (NO\({}_{3}\)-N) & & 0.1–7.0 mg/L \\ \hline
7. & Nitrite nitrogen (NO\({}_{2}\)-N) & & 0.001–1.2 mg/L \\ \hline
8. & Phosphate phosphorus (PO\({}_{4}\)-P) & & 0.001–0.5 mg/L \\ \hline
9. & Dissolved oxygen (DO) & Electrochemical sensor & 0.00–20.00 mg/L \\ \hline
10. & Biochemical oxygen demand (BOD\({}_{5}\)) & Dilution method & 0.1–2000 mg/L \\ \hline \end{tabular}
\end{table} 
Table 1: Specification of laboratory methods for physicochemical determinations of water [32; 33]. * Assessment of water quality was conducted with the use of water quality indices providing information on both the general water quality and the possibility of using water for various purposes (i.e., water supply, recreation, living conditions for fish fauna, agriculture, and industry), i.e., Oregon Water Quality Index (OWQI) [45], Overall Index of Pollution (OIP) [46], Dinius Water Quality Index (DWQI) [47], Indian Central Control Board Water Quality Index (CPCB WQI) [48], Universal Water Quality Index (UWQI) [49], and The National Sanitation Foundation Water Quality Index (NSF WQI) [50; 51; 52; 53]. The results were obtained by analyzing raw physicochemical data and then calculating the sub-index values for individual parameters based on formulas and determining the final value of the index based on the arithmetic or weighted mean of sub-indexes (detailed specification in Table 6).