Cal. Gov. Code § 23132
The boundaries of Plumas County are as follows:
Beginning at the corner common to Plumas, Butte, and Yuba, situated in the NW. 1/4 of Sec. 15, T. 20 N., R. 8 E., M. D. B. & M., and indicated by a large spruce tree standing in front of the Buckeye House marked "Corner of Plumas, Butte and Yuba" and running thence northeasterly by direct line to the corner common to Plumas, Sierra and Yuba in Slate Creek situated in the NE.1/4 of Sec. 31, T. 21 N., R. 9 E., M. D. B. & M., at a point where the third course or terminating north and south line of the survey of Keddie and Church, made June 19, 1866, crosses said creek; thence northeasterly up said creek to its intersection with the first north and south line of said survey in the NE. 1/4 of Sec. 11, T. 21 N., R. 9 E., M. D. B. & M.; thence north along said line to the initial point thereof, being the summit line of the ridge dividing the waters of the Feather River from the waters of the Yuba River, situate in the SE. 1/4 of Sec. 26, T. 22 N., R. 9 E., M. D. B. & M.; thence easterly, on said summit line, and east to "The Falls" about one mile below the outlet of Gold Lake;
Thence east to the range line between T. 21 N., R 13 E., and T. 21 N., R. 14 E., M. D. B. & M.; thence north on said range line, to the northwest corner of T. 21 N., R. 14 E., M. D. B. & M.; thence east on the line between T. 21 and 22 N., M. D. B., to the corner common to Plumas, Lassen, and Sierra, said corner being the southeast corner of Plumas and the southwest corner of Lassen, said point also being the corner common to Secs. 1 and 2, T. 21 N., R. 16 E., M. D. B. & M., and Secs. 35 and 36, T. 22 N., R. 16 E., M. D. B. & M.; thence northwesterly, on the southwestern irregular line of Lassen to the corner common to Shasta, Lassen, and Plumas; thence west nine miles more or less on the southern line of Shasta to the northeast corner of Tehama; thence southerly, on the ridge, being eastern line of Tehama, to the common corner of Tehama, Butte, and Plumas; thence southerly along the eastern boundary of Butte to the place of beginning.
Ca. Gov. Code § 23132