Founded in 1934, the Grand River Conservation Authority was the first watershed management agency in Canada.
It runs between the three cities and the region and is currently the largest in southern Ontario.
At 6,800 square kilometres, it's about the same size as the province of Prince Edward Island.
The Grand River watershed is home to the Six Nations of the Grand River Territory and the Mississaugas of the New Credit First Nation. Six Nations is the most populous First Nation in Canada.
Learn more here.