How can I find out / where can I find the length, "source" (beginning point), "mouth" (ending point) of the California portion of rivers?
For example, it's easy to find the length, source, and mouth of the Colorado River, which runs partly through California, but I'm just interested in the California part.
True, I can, through somewhat meticulous research, find the California beginning and ending of the Colorado River on a map, but where can I find the length?
"Googling" provides a plethora of info about the river as a whole, but no so much about just the California portion...
I have the same question for the Klamath (partly in Oregon) and Amargosa (partly in Nevada) rivers.