2023 California Delta Residents Survey

The Delta Residents Survey (DRS) was a household survey conducted in the Sacramento-San Joaquin Delta in Northern California in 2023 to better understand residents' attitudes on key social and environmental challenges in the region. 

The data were collected via a survey (available online through Qualtrics or as a print version), with survey invitations sent by mail to a random sample of 82,000 household addresses in the rural “Primary Zone” of the Delta (survey Zone 1), the suburban and urban “Secondary Zone” of the Delta (survey Zone 2) and Delta-adjacent “EJ Communities” in South Sacramento and South Stockton (survey Zone 3). Maps of the survey zones are available in project documentation and the Results Summary Report. The survey was available in English and Spanish. Over 2,300 responses were received, constituting a 2.9 percent response rate. 

The survey included 43 multiple choice and short response questions, broken up into five sections around key themes: 

• Sense of place and way of life
• Regional priorities, concerns, and quality of life
• Environmental and climate change experiences, concerns, and policy preferences
• Civic engagement and good governance
• Demographics

The research was conducted by a collaborative team of environmental social scientists across multiple research universities (UC San Diego, UC Davis, UC Berkeley, Oregon State University, and Sacramento State University) and was funded by the Delta Stewardship Council's Delta Science Program (a California State Agency). Significant community engagement and partnership efforts were carried out to improve the relevancy of survey questions and interpretation of data.

Additional resources, including summary report of results and other research products using the data, are posted on our project website as they become available: https://ktomari.github.io/DeltaResidentsSurvey/.

We also have a GitHub repository, where R scripts (and accompanying plain-text descriptions of the functions used that can be translated into other programming languages) are posted, which provide the easiest way for reading in the data and ensuring variable types are set correctly. We highly recommend using or referencing these scripts for the easiest and most accurate use of the data: https://github.com/ktomari/DeltaResidentsSurvey.
 

 Geographic Coverage:    California, Sacramento-San Joaquin Delta, Contra Costa County, San Joaquin County, Solano County, Sacramento County, Yolo County

Time Period(s):    2/2023 – 5/2023 (Spring 2023)

Universe:  Adults living in residences in the Sacramento-San Joaquin Delta

Data Type(s):    survey data

Collection Notes:   Data restrictions: 
To protect respondent privacy, certain geographic, demographic, and survey response variables belonging to the original dataset are restricted from general public dissemination. Users interested in obtaining these data must complete a Data Sharing Agreement for the use of confidential data, submit a Data Request Form to the research team that specifies the reasons for their request, research questions, and specific variables they seek to use, and obtain IRB approval or notice of exemption for their research. To learn more, first review the Data Sharing Agreement available in project documents and then review available materials in the "Restricted Use Data Information" folder.

Data format: 

• Public dataset is provided as a .csv
• Codebook explaining all variables in the dataset is provided as a .xls
• A .txt file is provided containing the hash code of the dataset file. It is recommended to obtain the hash code of the dataset csv you download and validate that it matches the hash code we provide in the text file. This ensures the data file has not been corrupted or changed in any way during the download process.

Resources for working with data:
We have a GitHub repository, where R scripts (and accompanying plain-text descriptions of the functions used that can be translated into other programming languages) are posted, which provide the easiest way for reading in the data and ensuring variable types are set correctly. We highly recommend using or referencing these scripts for the easiest and most accurate use of the data: https://github.com/ktomari/DeltaResidentsSurvey.

Methodology

Response Rate:    2.9 percent response rate overall

Survey zone 1 (Delta Primary Zone): 5.7% response rate
Survey zone 2 (Delta Secondary Zone): 2.5% response rate
Survey zone 3 (Delta EJ communities): 3.4% response rate

All response rates calculated following the American Association for Public Opinion Research (AAPOR) response rate calculator-v3. 

Sampling Frame:
The survey was distributed  to residential addresses in three survey zones (strata), based off of the legal boundaries of the Delta:

• Zone 1: (“Delta Primary Zone”, including Rio Vista): Rural area in the heart of the Delta.
• Zone 2: (“Delta Secondary Zone”): Surrounding the primary zone, includes suburban/ urban areas of cities of Antioch, Brentwood, Oakley, Pittsburg, Sacramento, West Sacramento, Stockton, Tracy
• Zone 3: Comprised of two urban areas, one in south Sacramento and one in south Stockton, lying outside of, but just adjacent to, the legal boundary of the Delta Secondary Zone (zone 2). This zone included communities known to bear disproportionate environmental harm burden. These areas are defined by California’s Community Air Protection Program1 (CAPP; responsive to 2017 Assembly Bill 617), which defined boundaries at a very local level for communities highly impacted by environmental harms. The program includes communities in South Stockton & South Sacramento/Florin, which the research team adopted for the 2023 DRS for the purpose of reaching Delta adjacent, highly impacted and socially vulnerable communities.

Residential address sampling was done using the U.S. Census geographies, specifically using 2020 Census Block Groups (CBGs), the finest scale spatial unit available. Sampling by CBG geography allows for more accurate comparison to full population characteristics (e.g. demographics) to assess the survey respondents for representativeness and weight the data appropriately. CBG boundaries do not perfectly overlap with Delta legal boundaries or the CAPP legal boundaries. Discrepancies between CBG boundaries and the zone boundaries were reconciled in the following ways:

• If part of a CBG is inside a zone and part is outside of all zones, include the full CBG in the zone.
• If a CBG falls into both zones 1 and 2, assign the CBG to whichever of the two zones has the largest population.
• If a CBG falls into both Zone 2 and Zone 3 (which only occurs in Stockton where these two zones overlap), those CBGs go with Zone 2.

Maps showing survey zones are available in project files and in the results Summary Report. 


Sampling rate: 
The survey was distributed to a stratified random sample of addresses within each survey zone. Sampling rates differed between zones due to population size, with the rural zone sampled at a higher rate and suburban/ urban zones sampled at lower rates.

• Zone 1: ~100% of households + traditional post office boxes (physical address does not receive mail) were sampled (4,372 residential addresses + 1,670 PO boxes invitations sent for a total of 6,042 invitations sent)
• Zone 2: 25% of households were sampled (59,175 invitations sent)
• Zone 3: 25% of households were sampled (16,940 invitations sent)

A total of 82,157 invitations were sent by mail. 

Collection Mode(s):   mail questionnaire; web-based survey

Scales:   Question types vary, including binary (yes/no) questions, select all that apply, and several Likert-type scales.

Weights:    The 2023 DRS dataset includes one person-level analysis weight variable ("WTFINAL") which incorporates sampling and nonresponse to adjust data to be representative based on demographics (gender, age, ethnicity, race, education, income) of the population in the sample frame. This weight variable should be used in all analyses that leverage all data. When evaluating different demographic subsets of the data, weights should be removed.

Detailed information on the weighting procedures applied are available in the Summary Report (Appendix C).

Unit(s) of Observation:    Individuals

Geographic Unit:    County in public data; restricted data include Census Block Group (CBG) identifiers

The following publications cite the data in this project.

• Rudnick, Jessica, Kenji Tomari, Kelly Dobbin, Mark Lubell, and Kelly Bidenweg. “2023 Delta Residents Survey Summary Report,” October 2023. https://ucdavis.app.box.com/s/34kmt02f87ohhbpij9hu0iesubm15781.