Western Terminal Lakes
All datasets · API reference · Dataset page on heimdallresearch.com
Monthly open-water area for six western terminal lakes (Great Salt Lake north and south arms, Salton Sea, Mono, Pyramid, Walker and Abert) from Sentinel-2 imagery since 2019, with an uncertainty range and a lake-gauge cross-check.
Status: In preparation. Version 1.0 is estimated for December 2026.
| Themes | water, deserts |
| Coverage | Great Salt Lake (both arms), Salton Sea, Mono, Pyramid, Walker, Abert |
| Period | 2019 to present |
| Resolution | Lake by month, from 10–20 m imagery |
| Free updates | Monthly, about two weeks after month end |
| Paid updates | Weekly, for any lake or reservoir you name |
| License | CC-BY-4.0 |
| Free | Monthly series for the six lakes, as files and through the API and MCP server with a free key. |
| Paid | Weekly series for any lake or reservoir you name, joined to its gauge and reservoir records. See Water observation histories. |
| Intended use | Tracking long-term change in the size of western terminal lakes, comparing lakes on one definition, and checking satellite area against gauge-derived area. |
| Not intended for | Water rights, engineering or regulatory decisions, volume or storage estimates, or dust emission estimates. |
Tables
Section titled “Tables”| Table | One row per | Fields |
|---|---|---|
| lake_monthly | lake_id, month |
8 |
Access
Section titled “Access”API: GET /v1/lakes, GET /v1/lakes/{lake_id}/monthly, GET /v1/lakes/{lake_id}/weekly (paid). See the API reference.
MCP tools: get_lake_series, get_download_link. See Use it in your AI assistant.
Files: CSV and Parquet on Zenodo and Hugging Face, with datapackage.json, a Croissant file and SHA256SUMS, from the first release.
How values are produced
Section titled “How values are produced”Each month, every usable Sentinel-2 view of each pixel is combined, so partly cloudy or partly covered days still count. Water is classified with standard spectral water indexes and thresholds chosen per scene, and area is measured in an equal-area projection inside a fixed reference outline. The uncertainty range spans the retained methods; the share of the lake seen at least once is published with every value. A month with no usable view stays blank.
Table lake-monthly
Section titled “Table lake-monthly”File lake_monthly.csv. One row per lake (or arm) per month.
One row per lake_id, month.
| Field | Type | Unit | Description |
|---|---|---|---|
lake_id |
string | Stable lake identifier. | |
month |
string | Calendar month, YYYY-MM. | |
water_area_km2 |
number | km2 | Monthly open-water area. May be empty. |
area_low_km2 |
number | km2 | Low end of the uncertainty range. May be empty. |
area_high_km2 |
number | km2 | High end of the uncertainty range. May be empty. |
seen_fraction |
number | Share of lake pixels with at least one usable view. | |
gauge_area_km2 |
number | km2 | Area from the gauge level and the USGS table. May be empty. |
quality_flag |
string | ok, low_coverage, bright_surface or ice. |
Limits
Section titled “Limits”- Salt crust and shallow margins confuse spectral water indexes; flagged months are marked.
- Winter ice and snow limit Mono and the northern lakes in some months.
- The reference outline is a working polygon, not a surveyed shoreline.
Sources
Section titled “Sources”| Source | Role | Terms |
|---|---|---|
| Copernicus Sentinel-2 Level-2A surface reflectance | Measured | Free and open under the Copernicus Sentinel data terms |
| USGS lake-level gauges (Water Data for the Nation) | Cross-check | Public domain |
| USGS elevation–area–volume tables, DOI 10.5066/P147WRTT | Converting gauge level to area | CC0 |
Required notices:
- Contains modified Copernicus Sentinel data 2019–2026.