Grassy Narrows, ON, is the common name for both a reserve and an Ojibwe First Nation. The reserve, legally known as English River Indian Reserve 21, is just over 41 km2 of land located about 55 km northeast of Kenora. There are 1,594 registered members of Grassy Narrows First Nation (also known as Asubpeeschoseewagong Netum Anishinabek), 971 of whom live on-reserve (2019). Grassy Narrows is a signatory to Treaty 3.
Approximately 90 per cent of Grassy Narrows residents suffer from mercury poisoning. The poisoning is the result of Dryden Chemicals Ltd. dumping mercury into the English-Wabigoon river system between 1962 and 1970. The effects of the pollution are ongoing, and have also affected Whitedog First Nation (also known as Wabaseemoong Independent Nations).