Etienne Brule Park is part of the Humber River Trail in Toronto, which is about 32km long. A lot of these trails can be reached by car, bus, subway or even Go Train, so there's really no excuse not to get out and experience them.
The Etienne Brule Park is just north of King's Mill Park, Humber Marshes and South Humber. It runs from Old Mill Road to Lundy Avenue. They've made plenty of improvements based on the Humber River Fisheries Management Plan. The plan is to improve the movement of the fish in the watershed and of course to protect the fish during the early stages of growth as well.
One of the first things you'll notice entering the park lands is the Old Mill Bridge which has been there since 1793 when Toronto's first Industrial building "The king's Mill" was built. It's purpose was to supply the wood for the construction of Fort York. The bridge today isn't exactly the same one, but it was modified in 1916. One further note about the Old Mill (Inn and Spa) and the Bridge is that they are now designated under the Heritage Act. Basically what that means in a nutshell is that historically it is documented, protected and never to be destroyed.
Going even further back to a day of September 19, 1615 when Etienne Brule became the first European to see Lake Ontario, maybe even the first to see Georgian Bay, Lake Michigan, Lake Superior and Lake Huron. He was the first to live among the native people and learn their ways. All this at a ripe of age of 20 years old.
Here's a .pdf file on the Humber River Fisheries Mgmt Plan