For the verification of the sanitary and environmental conditions of the surface water masses in the area of influence of the Sanitary Landfill and also any possible alterations in quality of the sub- basin of the Salvaterra stream, the São Mateus stream and the River Peixe (main river), the following sampling points are considered, the parameters and frequencies being listed in Table 4:
- Point 1 (upstream) –cistern for reception of the waters of the springs that are drained under the impermeabilisation layer of the Sanitary Landfill;
- Point 2 (downstream) – Salvaterra stream;
- Point 3 (downstream) – São Mateus stream;
- Point 4 (downstream) – River Peixe upstream from the confluence with São Mateus stream;
- Point 5 (downstream) – River Peixe downstream from the confluence with São Mateus stream.