So it's not a 4 wheeling event but I figured I'd throw it out there since there was some interest in Malakoff Diggins last time we wheeled through there. Saturday June 9 is their annual Humbug Day. From the website:

Revisit the exciting and controversial hydraulic gold mining era of the 1870’s! Enjoy Old Time music, barbecue picnic, homemade ice cream, wagon rides, craft demonstrations, gold panning, candle making and tin punching, old fashioned family games and prizes, storytelling, living history tours of scenic North Bloomfield, the world’s shortest parade, and shooting the water cannon! Cost: Parking Fee.

This may be the last time they have this event. The park is on the closure list. 🙁