California Data Exchange Center — reservoir storage
Monthly and daily storage, elevation, inflow and outflow for around seventy major California reservoirs, several with continuous records from the early 1950s, alongside published design capacities and long-term average storage for each.
Rights
- Licence
- No reuse licence stated
- Commercial reuse
- Not clearly stated
- Redistribution
- Not clearly stated
- Derivative use
- Not clearly stated
- Attribution required
- YesData from California Department of Water Resources, used under No reuse licence stated.
- Restrictions
- Freely viewable, but the publisher does not state an open reuse licence. Hydrionis cites and links rather than redistributing.
- Terms last checked
- 25 August 2026
Access and coverage
- Publisher
- California Department of Water Resources
- Website
- https://cdec.water.ca.gov/
- Geographic coverage
- California — around 70 major reservoirs
- Temporal coverage
- 1953 onwards
- Update frequency
- daily
- Formats
- json, csv, html, api
- Bulk download
- Available
- Registration required
- No
- Cost to Hydrionis
- Free
- Domains
- reservoir, drought
Notes
Assessed for ingestion on 25 August 2026 and refused. CDEC is the best reservoir dataset found in this sprint: a clean JSON API, seventy years of monthly storage for named reservoirs, and — uniquely among the sources examined — published capacities, which would have allowed Hydrionis to compute percentage full rather than only volume. It was refused because California DWR states no reuse licence. Its conditions-of-use page covers privacy and liability and is silent on copyright, redistribution and commercial reuse, so all three resolve to "unclear", and spec §4 and the access policy both treat silence as refusal rather than consent. Publicly accessible is not the same as reusable, and a source that would break the platform’s 100% commercially-reusable position is exactly the one not to make an exception for. USGS reservoir storage is used instead: it is a federal work and therefore public domain, covers more states, and reaches back to 1918, at the cost of publishing volume without capacity.