In this photo taken Wednesday, Jan. 20, 2010, black tubing is seen coming over a dam built along a creek for irrigation of marijuana plants at an abandoned marijuana growing site in the Sequioa National Forest near Fresno, Calif. With billions of dollars in drug profits on the line, Mexican traffickers are expanding their foothold in the domestic marijuana market taking over vast swaths of public lands.
Guest Commentary by Michael Carroll
Guest commentary by Phil Kerpen
By Mark Heller, Tribune
By Mark Scarp, contributing columnist
By Jerry Brown, contributing columnist