Longmont Dam Road Access serves as the primary trailhead for Button Rock Preserve, offering a wide dirt road that provides easy access along North Saint Vrain Creek with a fishing pier and parking area.

The location features a 60-vehicle parking lot (closed when full) and is open daily from one hour before sunset to one hour after sunset; note that dogs are prohibited as of May 2023.

This walk-in only access point provides opportunities for fishing, hiking, and wildlife viewing, with scenic trails branching into the preserve.