Editing Yellowknife (section)

=== Arsenic contamination ===
The area has elevated levels of arsenic due to the region's geology and past mining operations. The bedrock contains arsenopyrite, a naturally occurring mineral that contains arsenic, iron, and sulfur. Gold mining in the 20th century released large amounts of arsenic into the environment. The roasting process used to extract gold from arsenopyrite ores created arsenic trioxide as a byproduct, which was often released directly into the environment. 
The Giant Mine, which operated from 1948 to 2004, left behind 237,000 tonnes of arsenic trioxide waste on site. The mine is located 4 km north of Yellowknife's city limits. The Government of the Northwest Territories is working with researchers to monitor and study arsenic levels in the area. The Giant Mine Remediation Project is a billion-dollar cleanup effort that will take about 10 years to complete. There are several ongoing programs to monitor residents for elevated levels of arsenic.<ref>https://www.cbc.ca/news/canada/north/canada-150-betsina-family-nwt-1.4180681</ref><ref name="auto">{{Cite web|url=https://www.hss.gov.nt.ca/en/newsroom/arsenic-lake-water-around-yellowknife|title=Arsenic in Lake Water Around Yellowknife|first=Health and Social|last=Services|website=www.hss.gov.nt.ca}}</ref>