In southern Ontario, rivers and streams are part of a complex network. In these networks, tiny streams flow into other streams or rivers, which then flow into other rivers, lakes, or wetlands. The place where one river joins another river is a confluence. Two different waters mix together at the confluence, one not only increasing the flow of the other, but also changing its chemical makeup, temperature, and biota.

The confluence of some rivers forms enormous deltas that are visible from space. In contrast, the confluence of tiny Hanlon Creek with the Speed River is almost invisible. The creek tumbles out of a narrow gap in the trees, forming a tiny swirl of rapids when the Speed's levels are low. The merged flows will soon form another confluence, this time with the Grand River.