The page is about the area and Dawn Mine but I don't see anything about the Los Flores mines and water tunnels.
But anyway take the Cobb Estate entrance at Lake to the Echo Mt. trailhead. Follow the paved road, west of the canyon, past the ruins of the estate and the Los Flores water company water tank. Start the climb up the illegal trail to the power lines. After 20ft. a trail splits off right down into the gulch. Follow it for 30 mins. Lots of poison oak.
Was there today and found the fault lines and quartz veins they followed.