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Data Sources and Methods for the Release of Toxic Substances to Water Indicators

Methods

The indicators were calculated by summing the releases from the NPRI database for Canada, for each source, and for each province and territory for the years reported. Facilities report an estimate of their releases to water to the NPRI using one of the following methods:

  • continuous emission/release monitoring systems
  • predictive emission/release monitoring
  • source testing
  • mass balance
  • site-specific emission/release factors
  • published emission/release factors
  • engineering estimates

The source testing technique was the most common release estimation method used in the NPRI for the year 2011. Please consult the “Reporting to the NPRI” Web page for more details on these calculation methods.

Table 1: Number of NPRI facilities reporting Hg, Pb and Cd releases to water, Canada, 2003–2011
YearMercury
(number of facilities)
Lead
(number of facilities)
Cadmium
(number of facilities)
200376164129
200462172144
200553163139
200666163139
200765182145
200861180135
200985191147
201076193154
201174188152
Common*228974

Note: * Number of facilities common to all years

Source descriptions for the indicators were taken from the North American Industry Classification System (NAICS) used by Statistics Canada. The four-digit NAICS code, as reported by the facilities, was used for source classification.