Wide shallow tide flats combined with good water circulation and a native oyster population established Willipa Bay as a long standing business enterprise zone. Local First Nations people had been harvesting and trading oysters for a long period of time. The bay site was well situated for trade due to its location near the Columbia River.
The oyster business led to this area being one of the first areas where American settlers began business enterprises after what was to become Washington State was established as American territory. The very earliest days of the future Washington State being part of the United States coincided with the California Gold Rush. Money could be made supplying the miners and those that were profiting. This was during the brief pre Indian treaty days and the First Nations peoples were very much a part of the enterprise along with the new Americans. Oysters were gathered and loaded on ships that headed south to sell the oysters in San Francisco. (Apparently oyster harvests in San Francisco Bay rapidly were done in by a combination of over harvest and pollution)
There were businesses rivalries, boats were stolen, boats sank and eventually the bay was over harvested. However, better governance and the introduction of larger non native oysters from Japan has led to the bay now being a major oyster center along with some specific inlets in the Salish Sea.
Oyster shell mound at Bay Center
Oyster boats at Bay Center
The mud of the upper tide zone also holds secrets to the great coastal earthquakes
Tough muddy work has taken place at this inlet to find tsunami deposits and drowned forests
A final note, I came across this cartoon oysterwar. It takes place in Chesapeake Bay, but Washington State has had its share of oyster piracy as well http://washingtonlandscape.blogspot.com/2010/03/big-news-out-of-quilcene.html.