Water Well Drilling in California: Geology, Regulations, and Best Practices

California’s diverse geology and robust regulatory framework make water well drilling in the state a technically complex endeavor. Drillers must consider varying aquifer conditions – from the vast alluvial basins of the Central Valley to hard fractured-rock terrains in the mountains – as well as comply with state and county regulations for well construction. This article provides an overview of California’s groundwater geology, outlines permitting requirements, identifies key agencies involved in well regulation, and highlights practical considerations (like required forms, utility clearances, licensing, and new groundwater management rules) for drilling professionals. All information is drawn from authoritative sources to serve as a reliable reference for researchers and industry practitioners.

California Groundwater Geology: Aquifer Types and Regional Conditions

Groundwater in California is found in two primary aquifer types: alluvial aquifers (unconsolidated sediments like sand and gravel) and fractured-rock aquifers (water stored in cracks within hard bedrock). Alluvial aquifers underlie the state’s major valleys and basins, whereas mountainous and foothill areas rely on more limited fractured-rock storage. The alluvial basins – which number 515 statewide and cover about 42% of California’s area – contain the bulk of the state’s groundwater and tend to have the highest well yields. In contrast, fractured-rock areas (granite, volcanic, and metamorphic rocks of the Coast Ranges, Sierra Nevada, etc.) store relatively small amounts of water in joints and fissures, resulting in low-yield wells that can fluctuate seasonally.

Geological conditions vary markedly by region. The table below summarizes key characteristics and typical well depths for several of California’s hydrogeologic regions:

Understanding the prevailing geology at a drill site is crucial. In the Central Valley, for example, drillers can expect multiple aquifer zones with alternating clay layers, requiring careful well design to target the best water-bearing strata and prevent cross-flow. Coastal basin drilling might involve managing risks of saline intrusion by proper well placement and sealing. In fractured-rock terrains, a hydrogeologist may need to site wells where fracture density is highest, and the driller must be prepared for lower yields and perhaps drilling multiple test holes. By researching local hydrogeology (via groundwater reports or well logs from nearby sites) and designing wells accordingly, drillers can significantly improve outcomes in California’s varied settings.

Water Well Permitting Requirements in California

State vs Local Authority: In California, regulatory authority over water well construction is delegated primarily to local agencies (usually county environmental health departments) through local well ordinances. State law mandates that new wells meet minimum construction standards (outlined in DWR Bulletin 74-81 (Water Well Standards)), but counties and some cities serve as the Local Enforcement Agencies (LEAs) to issue well permits and enforce standards. In practice, anyone intending to drill, deepen, or destroy a well must obtain a permit from the local county or city authority before work begins. This applies to all types of wells, including domestic water wells, agricultural and irrigation wells, monitoring wells, and others, with few exceptions (e.g. oil & gas wells are regulated separately by state oil/gas agencies).

Permit Application and Standards: The permit process typically involves submitting an application describing the proposed well location, design, and purpose, along with a plot plan and any required fees. The drilling must be performed by a contractor holding a valid C-57 Water Well Drilling Contractor’s license (issued by the California Contractors State License Board). Permit conditions will require that the well is constructed in compliance with state and local standards – for example, regulations on minimum sanitary seal depth, casing materials, grouting of annulus, and setbacks from potential contamination sources (septic systems, manure pits, etc.) as specified in Bulletin 74 and the local ordinance. Counties have the authority to impose standards stricter than the state’s; many have adopted Bulletin 74 in full and added additional requirements tailored to local conditions (such as deeper seals in coastal areas to prevent seawater intrusion, or special rules in groundwater contamination sites).

Permit Oversight and Inspections: Once a well permit is issued, the driller must adhere to any conditions (such as a required surface seal thickness or distance from property lines). Local environmental health officials may conduct site inspections during and after drilling to ensure compliance. Upon completion, most counties require the driller to submit a copy of the state Well Completion Report and sometimes a disinfection or pump test report before final sign-off. Notably, a well permit in California is not a water rights permit – it grants permission to construct the well, not unconditional rights to pump any amount of water. However, some counties or Groundwater Sustainability Agencies (discussed later) may impose pumping or usage conditions as part of the approval in areas of limited supply. Well permits are typically valid for a set period (often one year) and may expire if the work is not completed in that timeframe.

Key Agencies Involved in Groundwater and Well Regulation

A number of state and local agencies play roles in managing groundwater and regulating well drilling in California:

• County Environmental Health Departments (Local Well Permitting Agencies): As noted, county (or some city) agencies are the frontline regulators for well construction. They review well proposals, issue permits, and enforce well standards. These departments ensure proper well sealing and spacing to protect groundwater quality and public health. They also often maintain local well databases and in some cases coordinate with groundwater management agencies on well approvals.
• California Department of Water Resources (DWR): DWR develops the statewide well construction standards (Bulletin 74) and updates them as needed. DWR also acts as the state repository for well data – drillers are required to file Well Completion Reports with DWR, and the department maintains a well log database and map application. DWR provides technical guidance to local agencies and has programs to assist with groundwater monitoring (such as CASGEM for water level monitoring). In times of drought, DWR offers tools and resources (e.g., dry well susceptibility maps) to help local governments respond to well outages.
• State Water Resources Control Board (SWRCB): The SWRCB is the state agency with broad authority over water quality and water rights. For wells, the Water Board (and its nine Regional Water Quality Control Boards) focuses on protecting groundwater from contamination. For example, if a proposed well is near a groundwater contamination plume or an underground storage tank site, regional board staff may impose requirements or review to prevent cross-contamination. The SWRCB’s Division of Drinking Water regulates public water systems – any well serving a public water system (15+ connections or 25+ people) must meet stricter construction and sampling requirements and obtain a permit to operate as a drinking water source. The State Water Board also manages programs like GAMA (Groundwater Ambient Monitoring and Assessment) to monitor groundwater quality statewide.
• Sustainable Groundwater Management Agencies (SGMAs/GSAs): In 2014, California enacted the Sustainable Groundwater Management Act (SGMA), which required the formation of local Groundwater Sustainability Agencies (GSAs) in medium- and high-priority groundwater basins. GSAs are typically consortiums of local counties, cities, and water districts established to manage groundwater sustainably. While GSAs do not issue well construction permits, they develop Groundwater Sustainability Plans and can influence pumping by requiring metering, reporting of extraction volumes, or establishing allocation schemes. Coordination between well permitting agencies and GSAs has become increasingly important – for instance, GSAs may request to review new well proposals to ensure they align with the basin’s sustainability goals. During recent drought emergencies, state directives have even required formal GSA input before certain well permits are approved (see next section).
• Contractors State License Board (CSLB): The CSLB licenses water well drilling contractors in California under the C-57 classification. To legally drill wells for hire, contractors must hold a C-57 license, which entails meeting experience requirements and passing an exam on well construction. The CSLB enforces contracting laws and can take action against unlicensed drilling activity or contractor misconduct. Well owners should always verify that their driller has a valid C-57 license in good standing.
• Other Agencies: Depending on circumstances, other entities can be involved. For example, the Department of Toxic Substances Control (DTSC) may oversee wells used for groundwater remediation or monitoring at cleanup sites. Similarly, in adjudicated groundwater basins (mostly in southern California), court-appointed Watermasters or water districts manage extraction rights, and new wells may need to comply with adjudication decrees. These cases are specialized, but drillers should be aware of any such local requirements beyond the standard county permit.

Well Logs and Required Documentation for Drillers

California law requires that the details of every new well drilled (or well modified or destroyed) be documented and reported. The driller must submit a Well Completion Report – often called a “well log” – to DWR within 60 days of completing the work. This report, historically known as Form DWR 188, includes information on the well location, depth, geology (soil/rock layers encountered), construction details (casing, screen, seal), and initial water yield. Well Completion Reports are confidential by law (not public records), but they are available to regulators and the well owner, and summary data is used for groundwater studies. DWR’s Online System of Well Completion Reports (OSWCR) allows drillers to file these reports electronically, creating a convenient digital submission process linked to the driller’s license.

Drillers should familiarize themselves with the required documentation and forms before starting work in California. Key references and forms include:

• DWR Bulletin 74-81: Water Well Standards (PDF) – the official statewide minimum well construction standards. (Bulletin 74-90 is a supplemental update covering monitoring and cathodic protection wells.) These documents detail requirements for casing, sealing, site selection, etc., and are the foundation of most county well requirements.
• Well Completion Report Instructions – DWR – guidance on how to complete and file well logs. DWR provides an interactive map and request system for obtaining copies of existing Well Completion Reports as well, which can be useful for researching nearby well data.
• Example County Well Permit Application (Orange County, PDF) – a sample of a local well permit form. While each county’s form will differ, this example shows typical information required (well location, purpose, driller info, proposed construction specs, site plan, etc.). Always obtain the current form from the specific county where you plan to drill.
• Underground Service Alert “811” Notification – (not a form per se, but a required step) the ticket confirmation from the 811 center after utility notification. Drillers should keep this reference number as proof of compliance with the excavation law (discussed below).

By completing all required paperwork – permit applications, well logs, and any other county-specific reports (such as drilling cuttings disposal manifests or pumping test results if required) – and by keeping copies on file, drilling contractors demonstrate professionalism and due diligence. Moreover, submission of accurate well logs is not only a legal obligation but contributes to the broader knowledge of California’s groundwater, aiding future hydrogeologic research and water management.

Utility Clearance: DigAlert 811 – Call Before You Drill

Before any excavation or drilling begins in California, it is legally mandatory to notify underground utility coordinators to prevent dangerous hits to buried lines. California’s “Call 811” law (California Government Code §4216) requires excavators (including well drillers) to contact the statewide 811 call center at least two working days before starting to dig. By calling 811 (which connects to regional notification centers Underground Service Alert – known as DigAlert in Southern California and USA North 811 in Northern California), a driller triggers a process where local utility companies are notified and will mark the locations of underground utilities (gas, electric, water, telecom, etc.) at the work site.

Compliance with 811 is critical for safety and is strictly enforced. After the call, one must wait for utilities to respond and mark their lines (usually within two business days). Drilling should only proceed once all known utilities are marked or cleared. The law provides heavy penalties (up to $50,000 or more) for willfully drilling without notification and causing utility damage. Additionally, if a drill rig does strike an underground line, the operator must immediately alert emergency services if it’s a gas or hazardous pipeline, and notify the utility and 811 center. Following safe excavation practices – including hand-exposing utilities in proximity to the borehole path – is part of every professional driller’s due diligence.

In practical terms, contacting 811 is straightforward and free. Drillers can call 811 or use online ticket systems to provide the location and scope of work. Make sure to request utility markings for the entire area where drilling and any related trenching will occur (e.g., for installing pump lines or electrical). Remember that 811 notification is required for each separate job location and is valid for a limited time (typically 14 to 28 days); if the project timeline extends, the ticket must be renewed. By always obtaining an 811 clearance before drilling, well contractors protect their crews, avoid outages, and remain in compliance with state law.

Other Considerations for Drillers in California

Contractor Licensing: As mentioned, operating as a well driller in California requires a C-57 Well Drilling Contractor license. This ensures the driller has demonstrated knowledge of proper well construction techniques and relevant laws. A licensed contractor is also required to have appropriate bonding and insurance. Engaging in well drilling without the C-57 license (or aiding unlicensed activity) can result in legal penalties and project shutdown. The licensing requirement helps maintain professional standards and protect landowners from substandard work.

Well Completion Reporting and Compliance: Drillers must remember to file the Well Completion Report (WCR) on time (within 60 days) and provide copies to the well owner and local agency if required. Failure to file a WCR is a violation of the Water Code and can result in fines or action against the driller’s license. In addition, if the well is a public supply well, the driller/owner may need to coordinate water quality testing and additional reporting for the SWRCB Division of Drinking Water. California’s well code also requires proper well destruction of any old or dry wells – a driller performing well abandonment must also obtain a permit and file a completion report for the destruction, certifying that the well was sealed according to standards to prevent it from becoming a vertical conduit for contamination.

Groundwater Management (SGMA) and New Well Restrictions: The Sustainable Groundwater Management Act (SGMA) is reshaping how groundwater extraction is managed in California’s overdrafted basins. While SGMA does not create a new state-run well permit system, it empowers local GSAs to manage pumping. In practice, this means drillers and well owners should be aware of any GSA rules or ordinances in their basin. Some GSAs have begun requiring new high-capacity wells to register or even obtain GSA approval for extraction volumes. Notably, during the recent drought emergency (2021–2022), Governor Newsom’s Executive Order N-7-22 imposed temporary requirements on new well approvals: in medium- or high-priority basins, local agencies could not approve a well permit without first obtaining written verification from the GSA that the well would not conflict with the basin’s sustainability plan (this primarily targeted agricultural and large wells). The order also mandated that counties assess whether a new well is likely to cause interference with neighboring wells or land subsidence before issuing a permit. This was an extraordinary measure during a severe drought, and it underscored the growing importance of coordinating well drilling with groundwater management objectives. Drillers should check if any such requirements (either residual from that executive action or new local GSA policies) apply in their project area. Even outside of emergency mandates, it is wise to consult the local GSA or groundwater manager for any guidelines on well spacing or pumping monitoring.

Drought and Water Shortage Conditions: California’s climate is highly variable, and periods of drought can lead to increased drilling as well as new regulations. During droughts, some counties have issued moratoriums on certain types of wells or expedited permits for replacement wells for dry domestic supplies. State and local officials may prioritize domestic household wells when aquifers decline, and drilling in overdrafted areas might face heightened scrutiny. Drillers should stay informed through the State Water Board and DWR announcements during drought periods. For example, the State Water Board’s Drinking Water program may maintain lists of areas where many wells are going dry, and DWR’s drought assistance programs can sometimes fund well improvements or deepenings for small communities. Additionally, when drilling in times of water scarcity, managing owner expectations is crucial – drillers may need to explain that deeper drilling does not always guarantee abundant water if the overall aquifer is depleted.

In summary, working as a water well driller in California demands both technical expertise and careful navigation of regulatory requirements. By understanding the state’s geologic complexities, obtaining all necessary permits and clearances, adhering to construction standards, and coordinating with the relevant agencies, drilling professionals can ensure successful projects that provide reliable groundwater supplies. California’s emphasis on groundwater management and protection means that the drilling community plays a vital role in safeguarding this precious resource for long-term sustainability.

Sources: California Department of Water Resources, State Water Resources Control Board, California Water Code, County Environmental Health guidelines, and the Sustainable Groundwater Management Act documentation.