Permit Sonoma › Instructions and Forms › WLS-048 Emergency Drought Standards for Well Construction

WLS-048 Emergency Drought Standards for Well Construction

Version: 04/19/2024

On March 28, 2022, Governor Newsom issued an Executive Order to address the continuing western drought (Note: this order was amended in March 2023 by Executive Order N-3-23). The order requires additional review of well permits by local jurisdictions and groundwater sustainability agencies, as specified by paragraph 9 of the order below.

To protect health, safety, and the environment during this drought emergency, a county, city, or other public agency shall not:

Approve a permit for a new groundwater well or for alteration of an existing well in a basin subject to the Sustainable Groundwater Management Act and classified as medium-or high-priority without first obtaining written verification from a Groundwater Sustainability Agency managing the basin or area of the basin where the well is proposed to be located that groundwater extraction by the proposed well would not be inconsistent with any sustainable groundwater management program established in any applicable Groundwater Sustainability Plan adopted by that Groundwater Sustainability Agency and would not decrease the likelihood of achieving a sustainability goal for the basin covered by such a plan; or
Issue a permit for a new groundwater well or for alteration of an existing well without first determining that extraction of groundwater from the proposed well is (1) not likely to interfere with the production and functioning of existing nearby wells, and (2) not likely to cause subsidence that would adversely impact or damage nearby infrastructure.

This paragraph shall not apply to permits for wells (i) that will provide less than two acre-feet per year of groundwater for individual domestic users, (ii) that will exclusively provide groundwater to public water supply systems as defined in section 116275 of the Health and Safety Code, or (iii) that are replacing existing, currently permitted wells with new wells that will produce an equivalent quantity of water as the well being replaced when the existing well is being replaced because it has been acquired by eminent domain or acquired while under threat of condemnation.

Screening for Exempt Wells

Well permits will be reviewed and screened to determine if the additional review under the executive order applies.

Public Water Supply Well

Water wells that serve a public water system or a state small water system as defined in section 116275 of the California Health and Safety Code for provision of piped water to the public for human consumption are exempt from additional review under the executive order.

Small Domestic Wells

Water wells that will provide less than two acre-feet per year of groundwater for individual domestic uses¹ are exempt from additional review under the executive order.

Small Domestic Wells must serve four (4) or less residential dwelling units to qualify as providing groundwater for individual domestic users. Wells proposed on vacant parcels may qualify as Small Domestic Wells if the vacant parcel is zoned for residential uses, and the applicant clearly states within the permit application the intent of the proposed well will be for individual domestic users.

Appendix A of Policy and Procedure 8-2-1 Water Supply, Use and Conservation Assessment Guidelines shall be used to determine whether or not a proposed well will provide less than two acre-feet per year of groundwater for individual domestic users. Alternative calculation methods may be provided in lieu of using Appendix A if the alternative calculation method is based on federal or state standards. Applicants may appeal decisions regarding annual water supply quantity determinations by submitting a Water Use Assessment Report prepared by a qualified professional in accordance with Permit Sonoma Policy and Procedure 8-2-1.

Exempt Wells are Public Water Supply Wells or Small Domestic Wells, and are not subject to additional reviews or documentation under the Executive Order.

Non-exempt wells are neither Public Water Supply Wells nor Small Domestic Wells, and may be subject to additional reviews or documentation under the Executive Order.

Review Process and Required Information for Non-exempt Well Applications

All well application for non-exempt water wells will require additional supporting information including the reports listed below. These reports may be submitted as separate documents or one comprehensive study. All reports must be prepared and signed by a qualified professional.

Well Interference Evaluation Report

The well interference evaluation will assess if the extraction of groundwater from the proposed well is likely to interfere with the production and functioning of existing nearby wells. Nearby well means any well within 500 feet of the location of the proposed water well. If there are no nearby wells, then well interference analysis is presumptively met. A site plan shall be provided that marks all nearby wells within 750 feet of the proposed well location.

Well interference evaluation will consider impacts to the production and functioning of neighboring wells due to both:

Drawdown of water level in neighboring wells due to pumping of the project well;
Contribution to a condition of overdraft in the local aquifer.

Best available information and data, including hydrogeology, monitoring well data, the distance between the proposed well and the neighboring non-project well(s), and well construction and operational configurations for the proposed well and neighboring wells should be presented. The evaluation should include a description of the geology and hydrogeologic characteristics of the aquifer including estimated transmissivity, storativity, and water levels.

Well construction information and operational configurations will include:

Expected well depth, screened intervals, and annular seal of the proposed well and neighboring well(s), if available.
The maximum monthly pumping rate of the proposed well;

Drawdown should be calculated using industry standard methods appropriate to the aquifer unit under consideration; such methods include the Theis Equation applicable for confined or unconfined aquifers (Theis, 1935). Drawdown should be calculated for day 30 of continuous pumping at the maximum monthly water use rate.

Trends in water level, and other publicly available information, should be used to assess overdraft in the local aquifer. Water levels of all publicly available monitoring wells within 0.5 mile shall be presented and evaluated.

The potential for the extraction of groundwater from the proposed well to interfere with the production and functioning of existing nearby wells shall be evaluated using the estimated drawdown in nearby wells and the potential to exacerbate a condition of overdraft in the local aquifer. The configuration of nearby well(s), including the depths of screened intervals and pump depth settings (if available) should be used to evaluate site-specific impacts.

The well interference evaluation shall provide a conclusion that is clearly stated as to whether the proposed well is likely to interfere with the production and functioning of existing nearby wells.

Subsidence Evaluation

Land surface subsidence is the change in land surface elevation caused by an increase in effective stress due to groundwater overdraft, tectonics, or other natural processes such as hydrologic isostatic loading. Subsidence as used in the Executive Order pertains to subsidence caused by extraction of groundwater, not tectonics. Subsidence may be elastic or inelastic. Elastic subsidence is recoverable as groundwater conditions change. Inelastic subsidence is unrecoverable and is primarily due to irreversible compaction of clay-rich sediments.

Available land surface subsidence datasets for Sonoma County do not indicate the occurrence of inelastic subsidence due to groundwater pumping². Given available information, the requirement for assessing land subsidence is waived for new or replacement non-exempt well permit applicants. Should information become available indicating changed conditions and elevated rates of land subsidence the requirement for evaluation of subsidence shall be renewed.

Wells within a Medium or High Priority Basin

Well locations will be evaluated to determine if the proposed well is within the boundaries of a groundwater basin subject to the Sustainable Groundwater Management Act and classified as medium-or high-priority. Within Sonoma County there are three medium or high priority basins: the Santa Rosa Plain; Petaluma Valley; and Sonoma Valley. The Zoning and Land Use Map Viewer includes the layer Priority Groundwater Basin and may be used to determine if the well location is within a priority basin.

Well application materials for non-exempt wells located within a medium or high priority basin will be referred to the applicable groundwater sustainability agency (GSA) for review. The well permit will not be issued until written verification from the GSA is received with an affirmative finding that the proposed groundwater extraction is not inconsistent with the applicable Groundwater Sustainability Plan and that the proposed groundwater extraction would not decrease the likelihood of achieving the sustainability goal for the applicable groundwater basin.

The GSAs may request additional information of the well applicant. Permit Sonoma will coordinate with the GSAs and update this guidance document to include additional application materials that the GSA may require for their review.

The three GSAs in Sonoma County are separate agencies that are not under the umbrella of the County. Their review process is outside of the control of Permit Sonoma or the County of Sonoma.

Definitions

Qualified Professional: A Professional Geologist, Certified Hydrogeologist or Civil Engineer acting within the scope of their license. A qualified professional must hold a valid license in the State of California and be able to demonstrate experience or expertise in groundwater hydrology.

Small Domestic Well: A water well that provides less than two acre-feet per year of groundwater for individual domestic users.

Public Water Supply Well: A water well furnishing water for human consumption and general use to five (5) or more service connections or serves an average of at least twenty-five (25) individuals daily at least sixty (60) days out of the year.

Non-exempt Wells: A water well that is neither a Small Domestic Well nor a Public Water Supply Well, as defined above.

Nearby Well: Any well within 500 feet of the location of the proposed water well.

Well or water well: means any artificial excavation constructed by any method for the purposes of extracting water from, or injecting water into, the underground. This definition shall not include: (a) oil and gas wells, or geothermal wells constructed under the jurisdiction of the department of conservation, except those wells converted to use as water wells; or (b) wells used for the purpose of (1) dewatering excavations during construction, or (2) stabilizing hillsides or earth embankments; or (c) infiltration galleries and springs.

Additional Information

For existing nearby wells, groundwater levels and trends, and subsidence data:

Sustainable Groundwater Management Act (SGMA) Data Viewer

References

Theis, C.V. 1935. The relation between the lowering of the piezometric surface and the rate and duration of discharge of a well using groundwater storage: Transactions of the American Geophysical Union, v. 16, p. 519-524.

Footnotes

[1] California Code of Regulations § 660. Domestic Uses. Domestic use means the use of water in homes, resorts, motels, organization camps, campgrounds, etc., including the incidental watering of domestic stock for family sustenance or enjoyment and the irrigation of not to exceed one-half acre in lawn, ornamental shrubbery, or gardens at any single establishments. The use of water at a campground or resort for human consumption, cooking or sanitary purposes is a domestic use.

[2] Recent land surface elevation measured by GPS and InSAR indicate that land surface elevation is relatively stable in Sonoma County with some areas with slight increases and other areas with slight decreases. Adopted groundwater sustainability plans for the Santa Rosa Plain, Petaluma Valley, and Sonoma Valley groundwater subbasins all found that no significant inelastic subsidence has occurred within any of the three subbasins due to groundwater pumping. Similar rates of surface elevation change were measured for areas outside of the three priority subbasins through the County.