California Code, Government Code - GOV § 23145

The boundaries of Shasta County are as follows:

Beginning at the northern line of Tehama, at the head of Bloody Island, in the Sacramento River;  thence to and down the eastern channel to the mouth of Battle Creek;  thence easterly, up Battle Creek, by the main channel, to the mouth of the middle fork, known as Digger Creek;  thence up Digger Creek to its head;  thence east to a point south of Black Butte Mountain, forming the southeast corner;  thence north, on the western line of Lassen, to a rock mound forming the northeast corner, on the southern line of Siskiyou;  thence west, on said southern line, to Castle Rock, forming the northwest corner;  thence southerly along Trinity Mountain to the head of Bee Gum Creek, forming the southwest corner;  thence easterly down Bee Gum, Middle Fork, and Cottonwood Creeks to the western channel of the Sacramento River;  thence, by direct line, to the point of beginning.