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A containment zone is defined as a specific portion of a water bearing unit where the Regional Water Board finds, pursuant to Section III.H of State Water Resources Control Board Resolution No. 92-49, Policies and Procedures for Investigation and Cleanup and Abatement of Discharges Under Water Code Section 13304 (hereafter “Policy”), that it is unreasonable to remediate to the level that achieves water quality objectives. The discharger is required to take all actions necessary to prevent the migration of pollutants beyond the boundaries of the containment zone in concentrations which exceed water quality objectives. The discharger must verify containment with an approved monitoring program and must provide reasonable mitigation measures to compensate for any significant adverse environmental impacts attributable to the discharge. Examples of sites which may qualify for containment zone designation include, but are not limited to, sites where either strong sorption of pollutants on soils, pollutant entrapment (e.g. dense non-aqueous phase liquids [DNAPLS]), or complex geology due to heterogeneity or fractures indicate that cleanup to applicable water quality objectives cannot reasonably be achieved.

The monitoring program designed by the discharger and approved by the region shall include any land use controls. Land use controls are recorded instruments, proposed by the discharger, and agreed to by the owner of the affected property. The land use controls restructure the present and future uses of the affected property and may include recorded easements, covenants, restrictions or servitudes, or any combination thereof, as appropriate. Land use controls shall run with the land from the date of recordation, and shall bind all of the owners of the land, and their heirs, successors, and assignees, and the agents, employees, and lessees of the owners, heirs, successors, and assignees. Such instruments shall provide for (a) amendment or rescission of the restructuring upon application of the holder of fee interest in the property and upon the approval of the Regional Water Board if warranted by changed circumstances (e.g., new information demonstrates that a modification to land use restriction is appropriate, the containment zone designation has been rescinded because water quality objectives have been attained throughout the containment zone, etc.), and (b) except for the restriction contained in the instrument, the establishment of a containment zone shall not prohibit the full use of enjoyment of the property.

Pursuant to Section III.H.10 of the Policy, the Regional Water Boards shall keep a master listing of all designated containment zones; and the State Water Board will compile the lists from the Regional Water Boards into a comprehensive master list. The master listing shall describe the location and physical boundaries of the containment zone, the pollutants which exceed applicable water quality objectives, and any land use controls associated with the containment zone designation. The Regional Water Board shall forward the information on the master list to the State Water Board and to the local well permitting agency whenever a new containment zone is designated. The comprehensive master list, showing sites with containment zones in the State, is provided below. Additionally, the State’s historical list, showing sites where the containment zone designation was rescinded, is shown below.

Comprehensive Master List of Containment Zones in the State

The following sites in California currently have containment zones:

Historical List of Containment Zones in the State

The following sites had containment zones at one time; the containment zones have since been rescinded:

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