Cal. Health & Safety Code § 115700

(a) Every person owning land in fee simple or in possession thereof under lease or contract of sale who knowingly permits the existence on the premises of any abandoned mining shaft, pit, well, septic tank, cesspool, or other abandoned excavation dangerous to persons legally on the premises, or to minors under the age of 12 years, who fails to cover, fill, or fence securely that dangerous abandoned excavation and keep it so protected, is guilty of a misdemeanor.
(b) Every person owning land in fee simple or in possession thereof under lease or contract of sale who knowingly permits the existence on the premises of any permanently inactive well, cathodic protection well, or monitoring well that constitutes a known or probable preferential pathway for the movement of pollutants, contaminants, or poor quality water, from above ground to below ground, or vertical movement of pollutants, contaminants, or poor quality water below ground, and that movement poses a threat to the quality of the waters of the state, shall be guilty of a misdemeanor.
(c) For purposes of this section, “well” includes any of the following:
1. (1) A “monitoring well” as defined by Section 13712 of the Water Code.
2. (2) A “cathodic well” as defined by Section 13711 of the Water Code.
3. (3) A “water well” as defined by Section 13710 of the Water Code.
(d) A “permanently inactive well” is a well that has not been used for a period of one year, unless the person owning land in fee simple or in possession thereof under lease or contract of sale demonstrates an intent for future use for water supply, groundwater recharge, drainage, or groundwater level control, heating or cooling, cathodic protection, groundwater monitoring, or related uses. A well owner shall provide evidence to the local health officer of an intent for future use of an inactive well by maintaining the well in a way that the following requirements are met:
1. (1) The well shall not allow impairment of the quality of water within the well and groundwater encountered by the well.
2. (2) The top of the well or well casing shall be provided with a cover, that is secured by a lock or by other means to prevent its removal without the use of equipment or tools, to prevent unauthorized access, to prevent a safety hazard to humans and animals, and to prevent illegal disposal of wastes in the well. The cover shall be watertight where the top of the well casing or other surface openings to the well are below ground level, as in a vault or below known levels of flooding. The cover shall be watertight if the well is inactive for more than five consecutive years. A pump motor, angle drive, or other surface feature of a well, when in compliance with the above provisions, shall suffice as a cover.
3. (3) The well shall be marked so as to be easily visible and located, and labeled so as to be easily identified as a well.
4. (4) The area surrounding the well shall be kept clear of brush, debris, and waste materials.
(e) At a minimum, permanently inactive wells shall be destroyed in accordance with standards developed by the Department of Water Resources pursuant to Section 13800 of the Water Code and adopted by the State Water Resources Control Board or local agencies in accordance with Section 13801 of the Water Code. Minimum standards recommended by the department and adopted by the state board or local agencies for the abandonment or destruction of groundwater monitoring wells or class 1 hazardous injection wells shall not be construed to limit, abridge, or supersede the powers or duties of the department, in accordance with Section 13801 of the Water Code.
(f) Nothing in this section is a limitation on the power of a city, county, or city and county to adopt and enforce additional penal provisions regarding the types of wells and other excavations described in subdivisions (a) and (b).