CEC - Taking Stock: Releases to water

North American facilities reported releases of 257 pollutants to water in 2009, for a total of more than 211 million kg. Two of these, nitrate compounds and ammonia, together comprised 91% of the total.

Readers are reminded that each country has specific reporting requirements for sectors, facilities and pollutants that affect the North American picture of industrial pollution. Using and Understanding Taking Stock.

Almost half (48.5%) of all releases to water were reported by water and wastewater treatment plants, with all but a few of them public sewage treatment facilities located in Canada. These public facilities are unique in that they receive and treat wastewater from a variety of sources – residential, commercial, industrial, as well as stormwater run-off. In the United States, public wastewater treatment facilities (called publicly owned treatment works, or POTWs) are not subject to TRI reporting and therefore releases by these US facilities are not included here. The dominant releases associated with the reporting water and wastewater treatment facilities are nitrate compounds (more than 49 million kg) and ammonia (47.5 million kg), as well as phosphorous (4.7 million kg).

Although most industrial activities resulting in discharges to surface water in Mexico are subject to RETC reporting, only 14 facilities in the water and wastewater treatment sector reported releases to water in 2009. Of the top 10 pollutants shown in the above figure, none is subject to RETC reporting and in Mexico this sector reported 5,426 kg, mainly of nickel and lead compounds and cyanides. The leading sector for releases to water in Mexico was pipeline transportation of crude oil. This sector, which is dominated by PEMEX, the national petroleum company, reported more than 48,000 kg in releases to water – of which 91% were nickel compounds, followed by chromium compounds (9% of the total).

More than 34 million kg of nitrate compounds were also reported released to water by the food manufacturing sector, with about 85% of this amount reported by meat processing facilities, almost of them in the United States. These facilities also reported releases to 14 water of smaller proportions of ammonia and other pollutants. In Canada, only 11 facilities in the food manufacturing sector reported releases to water, mainly of nitrate compounds (about 1 million kg), as well as ammonia and phosphorous. In Mexico, 40 facilities in the food manufacturing sector reported a total of 12,414 kg in releases to water of metal compounds such as arsenic, cadmium, nickel and mercury, with one grain and oilseed milling facility reporting two-thirds of the total. Mexico’s beverage manufacturing sector also reported just over 17,000 kg in releases to water, mainly of metals and their compounds, including nickel, lead, and chromium.

The third-ranked sector for releases to water in 2009 was paper manufacturing (mainly pulp, paper and paperboard mills located in Canada and the United States). These facilities reported approximately 14 million kg in releases to water of nitrate compounds, manganese, ammonia, methanol, and phosphorous. Mexican facilities in this sector reported approximately 17,000 kg released to water, with cyanides accounting for almost two-thirds. The chemical manufacturing sector, mainly located in the United States and representing a wide variety of processes and applications, reported over 13.6 million kg in releases to water of over 100 pollutants – with nitrates accounting for about 87% of the total. Other pollutants released to water included manganese compounds, ammonia, ethylene glycol and methanol.

Reported releases to water in 2009 reflect differences among the three countries, both in reporting requirements and completeness of reporting. Almost half of all releases to water were reported by public wastewater treatment plants located in Canada. In the United States, public wastewater treatment facilities are not subject to TRI reporting. In Mexico, very few facilities in this sector reported. North American facilities in a variety of sectors also reported releases of heavy metals such as lead, nickel, cadmium and mercury compounds. These pollutants, released to water in relatively small quantities, can be extremely toxic to human health and the environment.

Primary metal manufacturing facilities ranked fifth for releases to water, reporting about 13 million kg. About 60% of this amount was reported by iron and steel mills and ferroalloy manufacturers. Releases to water from all primary metal manufacturing facilities in 2009 were dominated by nitrate compounds, which represented about 93% of the total. The sector also reported releases to water of many other pollutants, among them ammonia, sodium nitrite, and manganese.

Pollutants such as nitrate compounds and phosphorous can contribute to nutrient loading in lakes and rivers, leading to problems like eutrophication and dead zones. Even relatively small releases to water of heavy metals and their compounds, such as lead, nickel, and cadmium, have the potential to be extremely toxic to human health and the aquatic environment. Releases of substances such as mercury, a persistent, bioaccumulative and toxic (PBT) pollutant, can have long-lasting, deleterious effects on fish and the humans and wildlife that feed on them. The topic of releases to water from North American facilities was explored in Taking Stock #13.