Inspiration for lyrics??

Ok, so if CCR is from California, what was the inspiration behind all the "river" songs that are so prevalent in the south and deep south, and in particular CCR incorporates a lot of seemingly southern culture in their music. Examples: Proud Mary, Green River, Born on the Bayou...

?

My understanding is that John was creating the southern river/bayou surroundings as a more interesting backdrop for his songs---nobody wants to hear songs about El Cerrito,right? Also, "Green River" was written about a real-life place in California; Putah Creek, where John and family would vacation in his youth---there's a place called Cody's Camp there too.