Laguna Lake is a shallow natural lake at the head of the Chileno Valley. It retains some water year round. The 200 acre lake is 0.5 mi wide and 2 mi long, straddling the Sonoma-Marin county line in northern California, United States. It is the source of Chileno Creek which flows 10 km west to Walker Creek. It was included in the Rancho Laguna de San Antonio Mexican land grant, which was given to Bartolomé Bojorquez in 1845. Laguna Lake is used extensively for migrating and breeding waterfowl and Agriculture. agr.