Teck said it spends about C$15-18 million (US$11.5-13.8 million) a year on water quality and aquatic health studies and monitoring.

The reports have been prepared by professional scientists and are part of the Elk Valley Water Quality Plan, which was approved in 2014.

The reports have been reviewed by the Environmental Monitoring Committee (EMC), a group that provides science-based and Ktunaxa Traditional Knowledge advice and input to Teck and the BC Ministry of Environment and Climate Change Strategy regarding monitoring designs and reports in the Elk Valley.

The mining process in the area generates large quantities of leftover rock that contains naturally occurring substances such as selenium, an element that is essential for human and animal health in small amounts.

Water from both precipitation and runoff flows through these rock piles and carries selenium and other substances, such as nitrate, into the local watershed.

If present in high enough concentrations in the watershed, those substances can adversely affect aquatic health.

Teck's goal is to implement solutions to stabilise and reverse the increasing trend of selenium and other substances to ensure the ongoing health of the watershed.

Overall, Teck said, the report findings confirm that the targets for selenium and other substances established in the Elk Valley Water Quality Plan are appropriate and protective of aquatic life. They also indicate that while concentrations of selenium and other substances are generally trending as expected, they are not affecting fish populations.

Effects on the percentage of some types of benthic invertebrates (certain types of mayflies) have been observed in specific downstream areas and further study work is being undertaken to determine the cause.

Selenium and nitrate are the two constituents observed to most frequently exceed BC water quality guidelines, and, as such, are a primary focus of the initial implementation of the Elk Valley Water Quality Plan.

Drinking water guidelines for selenium and nitrate are exceeded in some parts of the watershed, meaning that local health authorities should be consulted prior to use of surface water as a drinking water supply. It was also noted that groundwater from a small number (5 of 91) of wells exceeded the guideline for selenium. Further monitoring will be conducted of wells that exceed guidelines, as well as those that are within 30% of guideline.

Marcia Smith, senior vice president, sustainability and external affairs, at Teck said: "Water quality is very important to communities, indigenous groups and the more than 4,000 Teck employees in the Elk Valley.

"A lot of work continues to go into understanding water quality and aquatic health in the Elk River watershed, and we are pleased to share our data. We believe these reports will help people see the efforts underway to better understand and manage water quality in the area."

Kathryn Teneese, Ktunaxa Nation council chair, said: "The Ktunaxa Nation Council is very pleased to learn that Teck will be providing public access to water-related environmental monitoring reports on their website.

"There have been significant impacts to water in Qukin ʔamaʔkis (Elk Valley) due to coal mining, and transparency and a shared understanding of the current situation across indigenous, provincial, federal and state governments is important."

Living Lakes Canada's executive director, Kat Hartwig, added: "Transparency from all sectors, including industry, is essential for more effective collaboration amongst First Nations and non-First Nations government, academia and community groups in order to address water quality and quantity challenges which are only intensifying with climate change."