..."it could never happen here"...
Oregon's dead zone is bigger and badder this year, probably trying to compete with its more famous cousins like the one in the Gulf of Mexico.
The Oregon dead zone is now recognized as probably caused by people, despite learned opinion from a few years ago that it was a natural phenomenon.
Low oxygen water has crept into shallow waters this year, and the darn thing is spreading up the Washington coast. Crab fishermen have found dead crabs in their traps, and dead fish have floated up onto beaches.
If you've never seen the Oregon coast, this is not where you expect a dead zone. Rough and sometimes craggy, with open beaches and not a lot of shallow water, the ocean off Oregon is swept by fairly strong currents and whipped by waves even in the summer. The water is usually cold and few people live on the coast. Overall, this is not a typical recipe for a dead zone (more typical = shallow, enclosed areas with lots of nutrient runoff and fairly immobile water where plankton blooms can cook up, sizzle, and then rot into a stinky deadened broth).
Nobody would have believed it if told a decade ago that a human-caused dead zone would be wreaking havoc off the Oregon coast. It just ain't how Oregonians think about the wild coast. Thunder and tarnation.
BTW, for the record, the dead zones are called that not because everything dies. Some wicked slimy things thrive in so-called "dead zones," and what dies is just all the nice things that people like to eat.