# Central Valley Groundwater Map and Forecast: release 2026-09.5cdfad9c

Readings through 2026-09. Forecast 2026-10 to 2028-09 (months 1-24, the tested range). Built 2026-10-30 11:57.
Licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Input data keeps its own terms:

- Groundwater levels: California DWR, Periodic Groundwater Level Measurements (data.cnra.ca.gov, public domain); USGS CVHM2 observations
- Precipitation and temperature: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 2026-10-22
- Evapotranspiration: OpenET ensemble v2.1 (https://etdata.org), CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/); sampled at the wells
- Vegetation (NDVI): NASA MODIS MOD13A2 v061 (Didan, K., doi:10.5067/MODIS/MOD13A2.061), via NASA AppEEARS
- Crop cover: USDA NASS Cropland Data Layer
- River flows: USGS NWIS. Project flows and water-year indices: California DWR CDEC. Allocations: U.S. Bureau of Reclamation (CVP) and California DWR (SWP)
- GSA boundaries (i03) and groundwater basins (i08 Bulletin 118, critically overdrafted basins): California DWR, data.cnra.ca.gov, Creative Commons Attribution (http://www.opendefinition.org/licenses/cc-by)
- Ground elevation: USGS 3DEP 1/3 arc-second DEM and DWR surveyed station elevations. Recharge soils: USDA-NRCS gNATSGO. Canals: (c) OpenStreetMap contributors (ODbL)
- NOAA outlook scenario: NOAA Climate Prediction Center long-lead outlooks. Disadvantaged communities: California DWR i16 (2023), CC BY. Domestic wells: DWR Well Completion Reports; dry wells: DWR Dry Well Reporting System

## Cite

Gray, W. (2026). Central Valley Groundwater Map and Forecast, release 2026-09.5cdfad9c (readings through Sep 2026) [Data set]. CC BY 4.0. https://groundwater-map-175591637760.us-west1.run.app/release/2026-09.5cdfad9c

## Files

- `wells_forecast_outlook.csv`, `wells_forecast_normal.csv`: one row per map well, one column per forecast month, ft below ground. Outlook = NOAA outlook: CPC issue 2026-10, water year 2027, central run at 121.9 % of normal precipitation. Normal = 100 % of normal precipitation. Header lines (#) explain the flags.
- `wells_forecast.parquet`: the same two tables in long format (site_code, scenario, month, depth_ft).
- `wells.geojson`: the wells as points with their attributes and the forecasts at months 12 and 24.
- `surface_now.tif`: the kriged depth surface at the latest readings. `surface_outlook.tif`, `surface_normal.tif`: one band per forecast month. `surface_normal_low.tif`: a normal year's deepest month. GeoTIFF, EPSG:4326, ft below ground, NaN outside the forecast area.
- `gsa_summary.csv`, `subbasin_summary.csv`: the kriged average now and a year ago, the forecasts, RMS wells below their MT and the plan rule (GSAs).
- `release.json`: the release's metadata, its model's test results and file hashes. `SHA256SUMS`: checksums.

## The model

A statistical model trained on DWR monitoring-well readings: a graph neural network blended with gradient-boosted trees. No pumping input. Months 1-12 are tested on held-out years; months 13-24 on year 2 of three held-out periods. A kriged cell is about 5.7 by 4.4 km; it is the area's level, not a well's. Test results for this release are in release.json (`model`).