Martha Lake (California)

Martha Lake is a small, man-made reservoir located in Contra Costa County, California, within the Black Diamond Mines Regional Preserve. It is a popular destination for hiking, picnicking, and wildlife viewing.

The lake was created as part of the Black Diamond coal mining operations that flourished in the area during the late 19th and early 20th centuries. It served as a water source for the nearby town of Nortonville and the mining activities.

Today, Martha Lake is managed by the East Bay Regional Park District (EBRPD). While swimming and boating are prohibited to protect the water quality and fragile ecosystem, visitors can enjoy a 1.5-mile loop trail around the lake. The trail provides opportunities to observe various bird species, including ducks, herons, and songbirds, as well as other wildlife like deer and squirrels.

The surrounding area features remnants of the former mining community, including exposed coal seams and mine tailings, offering a glimpse into the region's industrial past. Interpretive signs along the trail provide historical and ecological information.