Daniel L. Monahan, M.D. opened Vein Surgery and Treatment Center of Northern California in 2001. The name changed to Monahan Vein Clinic in 2011. He is board-certified in surgery and a fellow of the American College of Surgeons. Treating vein disease is not something to learn in a weekend course. Dr. Monahan’s formal training included more experience in vein treatment than typical surgical training, and he carried this expertise into his practice.