Cal. Sts. & Hy. Code § 1172
When it has adopted plans and specifications for such work exclusive of maintenance, the board may set apart therefor from the road fund of the county, and from the funds of any district of which the division is a part, such sums as the board considers equitable.
The board shall not set apart from the funds of any such district less than 75 percent of the sum which bears the same ratio to the whole fund of the particular district as the assessed valuation of that part of the division lying in the district bears to the whole assessed valuation of the district. The board may set apart more than this percentage. The board shall cause the sums to be set apart in a fund known as the "permanent road fund of ____ division," specifying the division by name.
Ca. Sts. and High. Code § 1172