Deputy District Attorney Linda Witong said Alan Lawrence Ager, 59, also must register as a sex offender and pay restitution in an amount to be determined after a court review.
Ager pleaded guilty in September to one count of engaging in three or more acts of substantial sexual conduct with a child under age 14. Two lewd acts on a child charges were dropped.
He was arrested for inappropriately touching a boy on at least 30 occasions between October 2005 and November 2006. Police said the boy was 5 years oldwhen the molestations began.
The boy's mother informed authorities when she came upon Ager in a room standing next to her son whose pants were down, authorities said.
Ager is the former director of the Marin Alliance for Medical Marijuana and he served a year in jail in 1999 for growing hundreds of marijuana plants he claimed where for medical marijuana patients.