Put a number on the change.
Choose a reservoir and two dates from its available history. Compare the elevation, inspect each daily reading and take the source evidence with you.
Start · 2026-08-29678.78 ft
End · 2026-09-28674.77 ft
Each dot is an available observation. The vertical scale follows this selection; gaps are not filled or interpolated.
Inspect 31 dated observations
| Series date | Elevation (ft) |
|---|---|
| 2026-08-29 | 678.78 |
| 2026-08-30 | 678.66 |
| 2026-08-31 | 678.51 |
| 2026-09-01 | 678.38 |
| 2026-09-02 | 678.24 |
| 2026-09-03 | 678.08 |
| 2026-09-04 | 677.93 |
| 2026-09-05 | 677.78 |
| 2026-09-06 | 677.63 |
| 2026-09-07 | 677.49 |
| 2026-09-08 | 677.34 |
| 2026-09-09 | 677.21 |
| 2026-09-10 | 677.07 |
| 2026-09-11 | 676.94 |
| 2026-09-12 | 676.80 |
| 2026-09-13 | 676.68 |
| 2026-09-14 | 676.56 |
| 2026-09-15 | 676.43 |
| 2026-09-16 | 676.28 |
| 2026-09-17 | 676.13 |
| 2026-09-18 | 675.99 |
| 2026-09-19 | 675.86 |
| 2026-09-20 | 675.71 |
| 2026-09-21 | 675.57 |
| 2026-09-22 | 675.43 |
| 2026-09-23 | 675.31 |
| 2026-09-24 | 675.18 |
| 2026-09-25 | 675.08 |
| 2026-09-26 | 674.95 |
| 2026-09-27 | 674.83 |
| 2026-09-28 | 674.77 |
TWDB · twdb:lake-travis
Snapshot retrieved: 2026-09-29T01:45:15.047Z (UTC). These are series dates, not live readings.
Underlying dated history ↗ · Agency station record ↗ · Refresh status
End elevation minus start elevation.
A positive change means the recorded water surface rose; a negative change means it fell. The calculator compares two dates within the same reservoir series. Multiply the difference in feet by 0.3048 to express that difference in metres.
Worked example from this snapshot: Lake Travis measured 678.78 ft on 2026-08-29 and 674.77 ft on 2026-09-28. Subtracting 678.78 from 674.77 gives -4.01 ft (-1.222 metres) over 30 days. Inspect the source history ↗
Values are rounded for display after subtraction. Feet and metres describe a height difference, not a volume or a percentage of capacity. Absolute elevations can use different reference systems, so this tool does not rank lakes against one another.
Questions about lake level changes
Can I choose any historical date?
The date selectors contain the valid, unique observations in our current snapshot. Older dates outside that snapshot are unavailable here. We do not fill missing dates, estimate endpoints or replace a missing value with zero. Frozen research editions provide separate archived evidence where available.
Why did the lake rise or fall?
The elevation series alone does not identify the cause. Check separate evidence about rainfall, inflows, releases, withdrawals and evaporation before drawing conclusions. This tool reports the measured difference without attributing a cause.
Does a one-foot fall mean the lake lost one percent of its water?
No. Reservoir geometry and the agency’s capacity definition determine the relationship between elevation and stored water. Use published storage measurements for a volume comparison. Read our elevation and percent-full guide.
Are these live readings or a forecast?
These are dated daily source snapshots. The retrieval timestamp tells you when we fetched the source, not when every observation occurred. Source revisions can change future calculations. Check data status and consult the issuing agency for current conditions.
What is in the CSV download?
Every available observation in your selected interval, plus the endpoint dates, calculated difference, source identifier, agency links and snapshot retrieval time. Save the file to preserve the evidence behind a comparison.
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