In the interests of accuracy and, one hopes, compliance, I give you a precis from Canadain Yachting Magazine. These regulations
have been in force since 2012 (Emphasis added by me):
In summary, the new regs allow no sewage discharge of any kind in any waters within one mile of any shore. Discharge of raw sewage in salt water is permitted if the vessel is greater than three miles from any shore. This allows overboard discharge, for example, into the middle of the Strait of Georgia. But most boaters do much of their boating close to shorelines so are caught by these new regulations.
For vessels in restricted waters where there is not sufficient distance between shores, and where there is no pump-out alternative, an exemption allows overboard discharge, as long as it is on an ebb tide, the vessel is in the deepest possible water and it is making its maximum cruising speed in excess of four knots. Overriding this exemption is the caveat that no solid waste can be found on a shoreline, nor can there be any surface sheen resulting from such a discharge.
Where the discharge is said to have occurred there is no discharge permitted. However 3 NM to the noreastward, discharge is
permitted. For me 3 NM represents a one hour detour (tour/retour) if I'm bound along the straits, but is of no consequence when crossing the straits.
Tidal flows are quite strong in Porlier Pass. The offender may have thought he could take refuge behind the exemption allowing discharge in deep water
on a strong ebb. A flow of 4 knots is common in Porlier, whirlpools are plentiful and the depth
of water is some hundreds of feet.
But when staying in compliance is so easy, why be a pain :-)?