Chatsworth Nature Preserve, Protected area in San Fernando Valley, Los Angeles, United States.

Chatsworth Nature Preserve is a protected area in the northwestern section of Los Angeles that contains oak forests, open grasslands, and seasonal water pools. The property features multiple natural habitats that support diverse wildlife and plant communities throughout the year.

Chatsworth Reservoir, the last of 19 water-retention basins built by the City of Los Angeles for Owens Valley water, entered service in 1919 behind two earth-filled dams and two smaller dikes. In 1994 City Ordinance #169723, backed by Councilman Hal Bernson and community and environmental groups, limited the former reservoir grounds to a nature preserve, scientific study and education.

The name "Calera" is Spanish for limestone quarry or limekiln, recalling the Spanish missionaries who processed limestone here for adobe plaster. The land holds at least 1,000 years of human use: Fernandeño and Chumash people ground acorns and seeds in sandstone outcroppings, and in the 19th century Mexican cattle ranchers and Basque sheepherders worked it. Today the fenced grounds are opened to the public only for a yearly Earth Day event.

A chain-link fence encloses most of the preserve, and the Los Angeles Department of Water and Power limits general access to the enclosed portion to a once-yearly Earth Day celebration. On other days the grounds cannot be entered, so plan around that single event rather than a routine visit.

The kiln, Chatsworth Calera, is Los Angeles Historic-Cultural Monument #141, designated April 2, 1975. It burned limestone for lime used in concrete, mortar and whitewash during the Spanish/Mission and Mexican periods, not the 20th century. It now appears as a pit about fifteen feet deep and six and a half feet across, with walls of vitrified limestone and brick.