United States Reservoir Storage Dataset
Monthly mean storage for long-record United States reservoirs and lakes, some from the 1920s. The data family that makes drought legible: rainfall says what fell, flow says what ran off, and storage says what is actually available to supply people.
Methodology
Aggregated by Hydrionis from USGS daily reservoir storage. Values are published in acre-feet and converted to millions of cubic metres using the exact definition of the acre-foot. A month is published only where at least twenty days of record exist. Reservoirs need twenty-five years of record and five thousand daily values, and at most twelve are taken from each state so that coverage is national rather than Californian. Storage is published as a volume and not as a percentage of capacity: the capacities published alongside do not state whether they are gross, usable or conservation storage, and the three differ substantially.
What this dataset cannot tell you
Coverage
| Subjects | United States reservoirs with 25+ years of record, capped at twelve per state — 92 held |
|---|---|
| Period | 1914–2026 |
| Units | Mm³ |
| Update cadence | Monthly |
| Identifier | us-reservoir-storage v1.0.0 |
Fields
Data dictionary →Every metric this dataset carries, with the unit it is stored in and the geography level it is reported at. Full definitions are in the data dictionary.
| Identifier | Field | Unit | Reported at |
|---|---|---|---|
reservoir-storage-volume | Reservoir stored volume | Mm³ | reservoir-site |
Rights and access
Licence position
Open. Derivative use true; redistribution true; commercial reuse true.
- Applies to material authored by US federal agencies. Third-party material carried within a federal product may be separately protected.
Permitted uses
- Public display
- Derived analysis
- API delivery
- Bulk download
- Commercial use
Available to: Public, Developer, Research, Professional, Enterprise. These follow from the rights of the contributing publishers, not from a Hydrionis pricing decision — no access tier can widen what a publisher withheld.
Contributing sources
Suggested citation
Hydrionis (2026), United States Reservoir Storage Dataset, version 1.0.0. Retrieved from https://hydrionis.com/data/datasets/us-reservoir-storage/
Cite the version. Hydrionis datasets change as publishers release and as methods are revised, and a citation without a version cannot be checked later.
Changelog
Version 1.0.0 — 2026-08-25
First release. Hydrionis holds reservoir observations for the first time.
Additions
- Monthly mean storage for long-record United States reservoirs.
Getting the data
Machine-readable metadata for this dataset is at /api/v1/datasets/us-reservoir-storage.json. For bulk extracts, higher-volume access or commercial licensing, see data enquiries.