Copel periodically monitors the quality of the water in its reservoirs, assessing the limnological conditions in the area of influence of the hydroelectric generation projects, with a view to ensuring legal compliance and multiple uses of the waters.
In general terms, the monitoring of water quality in reservoirs is mainly guided by two Resolutions:
- ANA-ANEEL Resolution No. 127/2022: establishes that the person responsible for the concession must carry out four monitoring campaigns a year in at least one point in reservoirs with an area greater than 3 km².
- CONAMA Resolution No. 357/2005: legislation that establishes the reference standards of water quality to be met in rivers and reservoirs, according to each classification class.
Copel has water quality monitoring stations at all its plants, and the number of stations varies according to the characteristics of the reservoir, such as area, time of residence and history of water quality. Currently, the monitoring network has 27 monitoring stations in 07 generation projects, 14 of which are classified as river stations (upstream or downstream of the reservoirs) and 13 stations in the body of the reservoir.
Table 1 – Initiative, number and type of monitoring stations, campaigns per year, water body, and municipalities:
| Enterprise | Acronym | Seasons | Campaigns per year | Water Body | Municipality (PR) |
| Pequena Central Hidrelétrica Bela Vista | PCH BLV | 3 River / 1 Reservoir | 4 | Chopim River | Verê |
| Usina Hidrelétrica Governador Ney Aminthas de Barros Braga | UHE GNB | 1 River / 3 Reservoir | 4 | Iguaçu River | Reserva do Iguaçu |
| Pequena Central Hidrelétrica Derivação do Jordão | PCH DRJ | 1 River / 0 Reservoir | 4 | Jordão River | Reserva do Iguaçu |
| Usina Hidrelétrica Governador Jaime Canet Júnior | UHE GJC | 2 River / 3 Reservoir | 4 | Tibagi River | Telêmaco Borba |
| Usina Hidrelétrica Governador Bento Munhoz da Rocha Neto | UHE GBM | 2 River / 3 Reservoir | 5 | Iguaçu River | Pinhão |
| Usina Hidrelétrica Governador José Richa | UHE GJR | 2 River / 2 Reservoir | 4 | Iguaçu River | Capitão Leônidas Marques |
| Usina Hidrelétrica Governador Parigot de Souza – Upstream | UHE GPS Upstream | 1 River /1 Reservoir | 4 | Capivari River | Campina Grande do Sul |
| Usina Hidrelétrica Governador Parigot de Souza – Downstream | UHE GPS Downstream | 2 River / 0 Reservoir | 4 | Cachoeira River | Antonina |
The parameters analyzed at the river monitoring stations and at each depth in the reservoirs are presented in the following table.
Table 2 – Water quality parameters monitored – river and reservoir:
| River samples | Samples in reservoir (Prof. I) | Samples in reservoir (Prof. II*) | Samples in reservoir (Prof. III*) |
| pH | pH | pH | pH |
| Conductivity | Conductivity | Conductivity | Conductivity |
| Total phosphorus | Total phosphorus | Total phosphorus | Total phosphorus |
| Orthophosphate | Orthophosphate | Orthophosphate | Orthophosphate |
| Total number | Total number | Total number | Total number |
| Nitrate | Nitrate | Nitrate | Nitrate |
| Nitrite | Nitrite | Nitrite | Nitrite |
| Total Ammonia Nitrogen | Total Ammonia Nitrogen | Total Ammonia Nitrogen | Total Ammonia Nitrogen |
| Total inorganic N | Total inorganic N | Total inorganic N | Total inorganic N |
| Calcium | Calcium | DBO | DBO |
| Magnesium | Magnesium | COD | COD |
| Sodium | Sodium | Turbidity | Turbidity |
| Potassium | Potassium | Total Solids | Total Solids |
| Sulfates | Sulfates | Sulfates | Sulfates |
| Sulphides | Sulphides | Sulphides | Sulphides |
| Chlorides | Chlorides | Cell count (cel/mL) and identification of phytoplankton | |
| Alkalinity | Alkalinity | ||
| Total Solids | Total Solids | ||
| Settling Solids | Settling Solids | ||
| Turbidity | Turbidity | ||
| Total Coliforms | Total Coliforms | ||
| Thermotolerant Coliforms | Thermotolerant Coliforms | ||
| DBO | DBO | ||
| COD | COD | ||
| Oils and Greases | Chlorophyll-a | ||
Cyanobacteria cell count (cel/mL) and phytoplankton identification |
* Depths II and III refer to the depths defined in the IQAR methodology
It should be noted that the parameters analyzed at river monitoring stations differ from those analyzed at reservoir monitoring stations. In addition to the parameters detailed above, temperature and dissolved oxygen are measured meter by meter at reservoir monitoring stations, which have a distinctive feature: samples are usually collected at two depths, determined according to the IQAR methodology; however, if anoxia (absence of dissolved oxygen) occurs, a sample is collected at an additional depth (depth III).
Monitoring results are expressed through three indices¹:
- IQA – Water Quality Index: Calculated based on the methodologies of the São Paulo State Environmental Agency (CETESB). It is a composite index that aggregates nine key parameters (dissolved oxygen, BOD, pH, water temperature, turbidity, total nitrogen, total phosphorus, thermotolerant coliforms, and total solids), resulting in a quality score that classifies the water quality conditions of the water body.
- IET – Trophic Status Index: Calculated based on the methodologies of the São Paulo State Environmental Agency (CETESB). It indicates the degree of eutrophication of the water body—that is, nutrient enrichment—based on concentrations of total phosphorus and chlorophyll-a, which can lead to excessive proliferation of algae and cyanobacteria.
- IQAR – Reservoir Water Quality Index: Calculated based on the methodology of the Water and Land Institute (IAT). This index was developed to assess the water quality of reservoirs, taking into account the vertical distribution of parameters, especially those indicating oxygenation conditions at different depths. It assesses the behavior of dissolved oxygen in the water column, making it possible to identify the occurrence of phenomena such as thermal stratification and anoxia in the deeper layers, which are typical conditions in lentic environments.
All monitoring data feed the Water Quality Management System – QdA, software developed to provide Copel’s water quality management. The results are submitted to the environmental agency through annual reports, along with the reports on samples collected during the campaigns conducted in the corresponding period.
