saltchuck
Any body of saltwater, especially the ocean.
The ultimate consensus was to keep the de-Whited river Green to its Tukwila junction with the Black, the outlet of Lake Washington, then make it Duwamish the rest of the way to the saltchuck.
Where it comes from
Borrowed from Chinook Jargon saltchuck (“the sea”, literally “saltwater”), from salt (“salt”) (from English salt) + chuck (“water”) from Nootka č̕aʔak (“water”).
Adapted from the Wiktionary entry saltchuck (CC BY-SA 4.0).