The vessel operation restriction regulations are the key regulations.
They cover a number of factors, including speed. One of the things municipalities can apply to restrict is speed. However, speed isn't really a critical factor when it comes to the effects caused by wake boats, for instance. A wake boat can travel 10 kilometres an hour but still cause a four-foot wave. That's pretty major.
The regulations don't seem to have kept pace with the new technologies boat manufacturers are coming out with. The regulations need to take into account not just speed, but also the impact of boats, including stirring up sediment when ballasts are engaged.