I have no advice, but just had to say I'm extremely jealous!!

I've in fact only seen two garter snakes in the 4 college years (so excluding summers) and 2 full subsequent years living in MN. Both were this year. I think this year had a garter snake explosion... possibly related to the well-documented increase in mouse populations?

One of the two garter snakes actually got into my minnow trap in the garage, little did I know it could trap snakes also! The dog found the snake first and was really spooked by it, and now he's scared of the minnow trap.. lol

They'll go into their winter cycle soon enough.