Hey westcoast, I think I may have stumbled upon another origin for the sound you experienced last week.
According to this very sad
blog
from Seattle PI about a dead orca,
There have been reports of sonar activity in the Strait of Juan de Fuca in the past week and a
half and members of K and L pod were reportedly in the area at the time as well.
The original AP story about this poor orca states that biologists were aware of Naval sonar testing in the area last week. A
second article -- from King5.com reports:
(WARNING-graphic photos of dead orca)
The Canadian Navy was observed using its sonar last week in the presence of L Pod in the San Juan
Islands.
The San Juans aren't too far from you correct? So, I began wondering if humans could hear this testing, and I found this article from 2003:
The sonar "pings" were so powerful (>200 dB re 1 uPa) that they could be heard in air by visitors along the shoreline of San Juan Island.
Source--found near the bottom of the page
First, I get that the military needs to evaluate its gear, but it should never be allowed to do so near sensitive marine environments. Why can't
they do this far out in the open ocean?
Secondly, do you think it possible that this is what you heard?
-----------
After more searching, it looks like some volunteers listening to Salish Sea hydrophones at
orcasound.net... heard the sonar:
The sonar was
picked up shortly before 5 a.m. by a San Juan Island resident who helps monitor hydrophones for the Salish Sea Hydrophone Network.
"We stream them live on the Internet and that's what enabled some of our devoted listeners to pick up the pings," co-ordinator Scott Veirs said.
"It's a high-pitched chord and a complex set of tones.
Source
Unfortunately, no recording of it that I can find. The article also states that the Canadian Navy uses a lower frequency than the USN.
Well, just throwing another option out there.
Thanks! 
