California Code, Government Code - GOV § 25825

The board of supervisors may acquire, construct, reconstruct, alter, enlarge, lay, renew, replace, maintain, and operate within or without the county sewers, drains, septic tanks, sewerage collection and treatment works and other sanitary disposal systems; and storm water drains and storm water collection and disposal systems, provided, however, that the full costs thereof shall be borne by the properties benefited except to the extent that such costs may be borne by eligible county federal revenue sharing funds.

The board may make and enforce all necessary and proper regulations for the use of sewerage collection, treatment and disposal facilities not in conflict with the Constitution and the laws of the state. The board may collect compensation from private or public parties for the connection to and use of sewerage collection, treatment and disposal facilities. It may restrict the use of the facilities to the inhabitants of the county.