i take your theory one step further, that there is sort of a "food chain" here...

in terms of the unsavory people that hang out at different kinds of water, it seems to go:

ocean -> sound -> lakes -> rivers

with rivers having the most riff raff, and smaller ones being the worst. you've all seen the garbage and littering at the skook, and there's a squatter on the nisqually who lives next to the access on the dike in his van, and dumps all his garbage down on the rocks