The Clover Valley Lumber #4 is a Mallet steam locomotive built by Baldwin in 1924. In 1956, it was sold to the Feather River Lumber Company, where a red feather replaced the green clover on the saddle tanks. It only served at Feather River for a year before being sold to the Tahoe Timber Company. #4 was used as a stationary boiler for the mill before being retired from that in the 1960's. When the mill was removed, it was left on a section of track surrounded by a fence until being rescued by the Pacific Locomotive Association in 1974. They restored it to operational condition and it operated on the Castro Point Railway until 1986 when the PLA moved their operations to Niles Canyon. #4 was the last steam locomotive to be operated at Castro Point, being used to move equipment to the Richmond Belt interchange for shipment to Niles Canyon. Afterwards, it was stored in a warehouse in Freemont, CA until 2005. On January 8, the engine and the other PLA equipment were moved to join the rest of the collection at the Niles Canyon Railway. At some point, in the mid 2000's, work began to restore #4 to operational condition. The restoration was completed in 2013 and the engine continues to run at the Niles Canyon Railway to this day.