Two years after a 25-year reservation of use and occupancy for Leroy Martinelli’s ranch on Tomales Bay expired, several families are preparing to lose their homes and it’s uncertain which rancher will graze cows on the pasture in the future. 

Come July, the farmhouse and three trailers clustered around it on the roughly 250-acre Martinelli Ranch will be empty. It’s the consequence of a National Park Service policy that prohibits lease holders from subleasing housing…