WOW You must live in the same area as I do. We have had 40 and 50 million dollar pot growing busts by Mexican gangs. Lot of shaved heads driving Escalades with full "bling". And you are so correct, they dont leave. The ones who do work agriculture, end up doing other things and thus the will be a never ending "need" for cheap labor.
Oh, Sweetie, just pick an area. They're everywhere there is a forest or secluded park areas. Just found another story about it today.
http://towncriernews.blogspot.com/
Mexican marijuana growers deported
Three Mexican men arrested during a raid on a large outdoor marijuana farm near the Yuba River in July were deported this week after a Nevada County judge sentenced them to three years of probation. [snip---be sure to see the photos of these grows at link]