Texas: TWDB
Water Data for Texas (Texas Water Development Board): recent-conditions JSON and per-reservoir CSV files. Percent full = 100 × conservation storage ÷ conservation capacity, as defined by TWDB. Elevations are in feet above the vertical datum stated by TWDB for each reservoir.
TWDB disclaimer: The reservoir data are best estimates generated by the Texas Water Development Board using data collected by various data providers as well as by TWDB. TWDB makes no warranties (including no warranties as to merchantability or fitness) either expressed or implied with respect to the data or its fitness for any specific application.
USGS gauges (all states)
The USGS Water Data API (OGC API) provides the latest lake/reservoir elevation readings (parameters 62614 NGVD29, 62615 NAVD88, 00062 above gauge datum) and daily means used for trends. We include sites USGS classifies as “Lake, Reservoir, Impoundment” with a reading in the last 7 days. Elevations are in feet above each gauge's own datum, so values are not comparable between lakes. USGS data are provisional and subject to revision; some gauges are operated by partner agencies.
U.S. Bureau of Reclamation
RISE (Reclamation Information Sharing Environment) provides daily reservoir elevation and storage for Reclamation reservoirs in the western US. Data are provisional unless otherwise noted.
U.S. Army Corps of Engineers
For a pilot set of Corps lakes we use the public CWMS Data API: hourly pool elevation and the project's published location levels (top of conservation pool, which can be seasonal, top of flood-control pool, top of inactive pool, pool of record, top of dam). Where a Corps lake already has a TWDB page (Lake Texoma), we keep TWDB's numbers and add the Corps' reference levels. USACE data are provisional.
Where the same lake is covered by more than one source, we use one source per page (TWDB first in Texas, then USACE, then Reclamation, then USGS).
Weather
Forecasts come from the National Weather Service API (api.weather.gov) for each lake's gauge location. The “Worth going today?” label is a simple automatic rule based on forecast wind and rain chance – it is not a safety assessment.
Staff gauge graphic
The gauge on each lake page is drawn from real values only: the current reading, the observed range over the last 12 months (or the period available) and, for Texas reservoirs, TWDB's conservation (full) pool elevation. If a source publishes no full-pool value, none is drawn.
Derived numbers
7-day, 30-day and year-ago changes, records and the “normal range for this date” (25th to 75th percentile and median of the same calendar date, ±3 days, over up to 30 past years) are calculated by us from the agencies' series. Older TWDB records may be monthly. All data are provisional and may be revised.
Site last built: 2026-10-25 21:05 UTC.