In 1923, the Lighthouse Service decided to mark this navigational hazard, and a small white shack with a pitched red roof was placed on the sloping point some eighty feet above the water. The structure housed two lens lanterns and a twelve-inch electric siren, for which the keepers at Lime Point were responsible. A telephone and electric line was strung to the point on poles, allowing the Lime Point keepers to listen-in on the semi-automated station. Still, the keepers were required to travel to Point Diablo weekly to clean the light and oil the fog signal.
An array of solar panels now powers the modern beacon positioned atop the shack. The light flashes every six seconds, and when necessary the fog signal alerts mariners to the presence of menacing Point Diablo.