Strange. I just did a dive across the Strait of Juan de Fuca (Salt Creek) and visibility was terrible there too. I've never seen it like this in the Straits at this time of year. Maybe it's because we usually don't get this many sunny days in a row.
Could also be the fairly large tidal exchanges ..... there seems to have been more big changes over short periods of time this year than I've seen in a while.
C.