Absolutely. I would also say you could even do it by reference to a map, recognizing that there are many unnamed waterways and that the list might be very long by the end of the day.
In Alberta we have done the same thing, again with respect to fisheries, and in fact there are maps referenced in the act itself. These can be updated as well, in a similar way to how a regulation can be updated. So if our original map were found to be deficient, we could amend it as well.