DWR's Basin Characterization Program

DWR has a long history of studying and characterizing California’s groundwater aquifers as a part of [California’s Groundwater (Bulletin 118)](https://water.ca.gov/Programs/Groundwater-Management/Bulletin-118 "California’s Groundwater (Bulletin 118)"). [California's Groundwater Basin Characterization Program](https://water.ca.gov/Programs/Groundwater-Management/Bulletin-118/Basin-Characterization "California's Groundwater Basin Characterization Program") provides the latest data and information about California’s groundwater basins to help local communities better understand their aquifer systems and support local and statewide groundwater management.  

Under the Basin Characterization Program, new and existing data (AEM, lithology logs, geophysical logs, etc.) are integrated to create continuous maps and three-dimensional models. To support this effort, new data analysis tools have been developed to create texture models, hydrostratigraphic models, and aquifer flow parameters.  Data collection efforts have been expanded to include advanced geologic, hydrogeologic, and geophysical data collection and data digitization and quality control efforts will continue. To continue to support data access and data equity, the Basin Characterization Program has developed new online, GIS-based, visualization tools to serve as a central hub for accessing and exploring groundwater related data in California. 


More information is available on the [Basin Characterization Program webpage](https://water.ca.gov/Programs/Groundwater-Management/Bulletin-118/Basin-Characterization "Basin Characterization Program webpage").

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# [Maps and Models](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/6b4823ed-e1e6-4a91-b1c6-f88423962f90 "Maps and Models")

Integrated datasets are used to develop state‑stewarded maps and 3D models describing aquifer structure, sediment textures, hydrostratigraphy, and groundwater‑flow properties. Products are updated as new data become available.

- Texture Models  
- Hydrostratigraphic Models  
- Aquifer Recharge Potential Maps  
- Extent of Corcoran Clay  
- Base of Freshwater  

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# Groundwater Basin Investigations #

DWR conducts investigations at multiple scales to develop state‑stewarded maps and models of California’s groundwater basins.

##Local Investigations 

+ [Madera & North Kings](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/8400c923-e18d-4ac5-958b-82f88e5af4f8 "Madera & North Kings"): AEM and tTEM data collection, lithology log digitization, texture model development, aquifer recharge potential mapping analysis.
+ [Pajaro](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/043aaa87-5c5d-433e-9afe-80f6966ca3ad "Pajaro"): AEM and tTEM data collection
+ [Western San Joaquin Valley](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/c2633b9c-cd34-445b-ac2d-4a5b49eb881d "Western San Joaquin Valley"): AEM data collection, lithology and geophysical log data digitization, texture model development.
+ [Prospect Island](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/b96e8832-d8af-416e-abcd-9240f7fb33d4 "Prospect Island"): AEM data collection, FloaTEM data collection test.

##Regional Investigations

+ [Sacramento Valley](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/fed9f9dd-fd0d-4ef6-a21b-a8835404b3c6 "Sacramento Valley"): AEM data collection, texture model development, aquifer recharge potential mapping analysis. 
+ [Four County Area of San Joaquin Valley (Madera, Fresno, Kings, and Tulare counties) ](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/a19efaf7-c0c0-4816-bcdc-1c1010a38ab3 "Four County Area of San Joaquin Valley (Madera, Fresno, Kings, and Tulare counties) "): AEM data collection, data digitization, texture model development, hydrogeologic conceptual model development, clay delineation, subsidence potential and mitigation, and aquifer recharge potential mapping analysis.
+ [San Joaquin Valley](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/19ea1234-6545-41c9-aeb2-f655d6599286 "San Joaquin Valley"): AEM data collection, data digitization, texture model development, hydrogeologic conceptual model development, clay delineation, subsidence potential and mitigation, and aquifer recharge potential mapping analysis.

##Statewide Investigations
+ [Statewide AEM Surveys](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/c9297796-80fb-4a0c-9464-5ec7a12c24bf "Statewide AEM Surveys"): AEM data collection, geophysical and lithology log data digitization.


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# Data Collection & Digitization #

## [Collected Geophysical Data](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/32347fa2-cadb-4994-88aa-6e9a87914c4e "Collected Geophysical Data")

Methods include:

- Airborne electromagnetics (AEM)  
- tTEM (towed TEM)  
- FloaTEM (water‑borne TEM)  
- Borehole geophysical logging  

## [Digitized Lithology and Geophysical Logs](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/942aa75e-8727-4e12-84a6-280b5896f3b0 "Digitized Lithology and Geophysical Logs")

Digitized logs support regional and statewide interpretations and are integrated into OSWCR.

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#Analysis Tools and Process Documents

Tools and guidance documents support integration and analysis of geologic, geophysical, and hydrogeologic datasets.

##[BCTools](https://data.cnra.ca.gov/dataset/dwr-basin-characterization-bctools ""BCTools") 
Open‑source tools for hydrostratigraphic modeling, sediment‑texture modeling, and aquifer‑parameter estimation.


##[Aquifer Recharge Potential Mapping](https://data.cnra.ca.gov/dataset/dwr-basin-characterization/resource/7d33d618-38bc-4511-834c-6e791695f8e2 "Aquifer Recharge Potential Mapping")
Methodology for identifying locations that have relatively higher potential for managed aquifer recharge. 

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# Data Visualization #

##[SGMA Data Viewer: Basin Characterization tab](https://sgma.water.ca.gov/webgis/?appid=SGMADataViewer#basincharacter "SGMA Data Viewer: Basin Characterization tab")

Provides maps, profiles, and depth slices of:

- Recharge potential  
- Texture model depth slices  
- Statewide AEM datasets  
- Lithology and geophysical log locations  
- AEM profiles  

##[California's Groundwater Subsurface Viewer](https://sgma.water.ca.gov/subsurfaceviewer "California's Groundwater Subsurface Viewer")

Interactive 2D/3D views of AEM resistivity, coarse‑fraction data, lithology logs, and related datasets.

Demo videos:

+ [Demo - AEM Data](https://cadwr.box.com/s/n0r66gkq4zoso0n9i6vb2o42uzcoq17s "Demo - AEM Data") 
+ [Demo - tTEM data](https://cadwr.box.com/s/a1mlh8wh2dagya4uahlxsbm9b79x44lp "Demo - tTEM data") 


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# Relevant Publications #



+ California Department of Water Resources, 2025, [California’s Groundwater: Bulletin 118 – Update 2025](https://data.cnra.ca.gov/dataset/calgw_update2025 "California’s Groundwater: Bulletin 118 – Update 2025"), Chapter 3: Natural and Built Groundwater Infrastructure. 

+ Dlubac, K., Springhorn, S., Brezing, B., Altare, C., and T. Godwin, 2024, [California's Statewide Airborne Electromagnetic Surveys and Preliminary Hydrogeologic Interpretations](https://www.conservation.ca.gov/cgs/documents/publications/california-geology-magazine/CG_2024-AEMsurveys.pdf "California's Statewide Airborne Electromagnetic Surveys and Preliminary Hydrogeologic Interpretations"), California's Geology Magazine, pp. 18-31. 

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# Presentation Recordings
Selected presentation recordings on Basin Characterization Program efforts. 

+ [BCTools Overview](https://cadwr.box.com/s/utu3si1lyyfg9ywbi8c92etp7kl4kaib "BCTools Overview"), Basin Characterization Team, Jack Baer, Woodard and Curran, Vivek Bedekar, SSPA, *Basin Characterization Exchange*, June2026
+ [Basin Characterization Program Overview](https://cadwr.box.com/s/ygobghqthe2i98lultjdzqvk3y74f7dp "Basin Characterization Program Overview"), Steven Springhorn and Katherine Dlubac, DWR, *Basin Characterization Exchange*, March 2026
+ [Aquifer Recharge Potential Mapping](https://cadwr.box.com/s/1okat2cbl3h75hm1nxtvpjmje2llg95t "Aquifer Recharge Potential Mapping"), Basin Characterization Team, Mesut Cayar, Woodard and Curran, *Basin Characterization Exchange*, April 2025
+ [California's Groundwater Bulletin 118 - Update 2025](https://cadwr.box.com/s/wvglzpa4l7nye0f21n03nvzujazs887t "California's Groundwater Bulletin 118 - Update 2025"), Emilia Wisniewski, Mandy Ott, Katherine Dlubac, DWR, *Basin Characterization Exchange*, November 2025

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# Basin Characterization Exchange #

The Basin Characterization Exchange (BCX) is a meeting series and network space for the Basin Characterization community to exchange ideas, share lessons learned, define needed guidance, and highlight research topics. Meetings are generally held the third Tuesday of each month, 12:30–1:30 pm (PST).

+ [Join the BCX listserv](https://forms.office.com/g/VgNif0iEuE "Join the BCX listserv") 
- Visit the [BCX Hub](https://cadwr.box.com/v/BasinCharacterizationExchange "BCX Hub") for schedules and materials  

Tags: AEM, Airborne Electromagnetic, aquifers, basin characterization, bulletin 118, geophysical logs, geophysics, hydrostratigraphic model, lithology logs, sgma, texture model
Organization: California Department of Water Resources