Cal. Gov. Code § 23103
The boundaries of Amador County are as follows:
Beginning at the southwest corner, in the Mokelumne River, on the eastern boundary of San Joaquin; thence up said river to its junction with the north fork of said river; thence up the said north fork to the line of Alpine, being at a point south of the common corner of Amador, Alpine, and El Dorado, which is in the center of the Amador and Nevada road, in front of Z. Kirkwood's house; thence north by the line of Alpine to said common corner, thence westerly along said road to a point east of the source of the south fork of the south fork of the Cosumnes River, thence west to said source; thence down the south fork of the south fork and the south fork and the main Cosumnes River to the easterly line of Sacramento; thence by the eastern lines of Sacramento and San Joaquin to the place of beginning.
Ca. Gov. Code § 23103