I recently bought some Craigslist furniture from a retired Alameda school teacher. While admiring the poster on his wall he threw it in with the sale and mentioned the state handed these out frequently to elementary school teachers for some time. I just scanned it and provided a copy here, a higher resolution copy of which is available on Flickr by clicking the image:
This map was prepared by the Irrigation Districts Association of California, which changed its name in 1973 to the Association of California Water Agencies (ACWA). I don't believe the organization creates these sorts of maps any more, maybe since the era of big dams and the associated propaganda is over. I suppose the Water Education Foundation has taken on this role, but I doubt they are sending such maps to elementary schools. Would be nice to see California's children a bit more educated on where their water comes from and how vital these resources are to California.
It wasn't until after I did the scan that I found out David Rumsey already posted a very high quality version of the map, along with a more modern 1983 version. I tend to prefer the cartoon look of the 60's map.