Volume of Industrial Effluent Discharges
Total volume of industrial effluents discharged into Quebec waterways by sector from 2006 to 2023 — showing which sectors discharge the most water and how volumes have evolved over time.
Total industrial effluent discharged into Quebec waterways fell 27% between 2006 and 2023, from roughly 711 M m³ to 519 M m³ per year. Pulp and paper remains the dominant sector (59% of total volume in 2023), though its share has declined as facilities were closed or modernized. The minerals and metals transformation sector grew sharply from 37 M m³ in 2006 to a peak of 210 M m³ in 2019, before falling back to 78 M m³ in 2023. These variations reflect changes in production capacity and industrial processes.
The Mont-Wright mining site stands out as the highest-volume discharger (67 M m³/yr average 2019-2023), roughly 2.5 times more than the Westrock/La Tuque paper mill. Yet its TSS load is far lower (293 t/yr vs 1,126 t/yr for Westrock), illustrating that effluent volume is not a direct proxy for pollution load. Mining sites discharge large volumes of process water and mine drainage that are relatively dilute.
The declared effluent volume from the minerals and metals transformation sector dropped sharply from 184 M m³ in 2018-2019 to 78 M m³ in 2022-2023. This drop coincides with changes in reporting coverage — a few large sites having modified their status — and does not necessarily reflect an actual volume reduction. Data for 2022-2023 in this sector should be interpreted with caution.
-27%
Total industrial effluent volume dropped 27% between 2006 and 2023 (from 711 M m³ to 519 M m³/yr). Pulp and paper, representing 59% of the 2023 total, cut its volumes by 40% (from 509 to 305 M m³/yr).
Mont-Wright
Mont-Wright (mining) is the top site by effluent volume (67 M m³/yr on average), more than any paper mill. Yet it ranks 7th for TSS (293 t/yr), showing that its process water is relatively dilute in pollutant load.