WATERTOWN, S.D.  (KWAT) — The approval of medicinal and recreational marijuana in South Dakota by voters this month is creating some big challenges moving ahead for the state’s law enforcement agencies that have police K-9 programs.

Watertown has two police dogs that are trained to hit on six controlled substances–one of which is marijuana.

But on July 1, possessing small amounts of that drug will no longer be illegal.

Kirk Ellis is a Watertown Police Department Captain and a former K-9 officer.

Ellis says it’s very difficult to “retrain” a certified K-9 that has been taught to detect marijuana.

He says South Dakota can look to what other states have done with their police dogs following the passage of marijuana laws.

Ellis says purchasing, training and certifying a police K-9 can cost upwards of $10,000.