September notebook: lake changes and the next tide window
A dated look at available September lake readings, plus the coverage and limits of seven NOAA tide references.
What a week of lake readings can tell you.
A reproducible snapshot note, updated with the source bundle. Interpretation is limited to the available measurements.
Monthly editions
Three lakes, the same comparison rule
For each reservoir, subtract the daily elevation exactly seven calendar days earlier from the latest headline reading. A positive number indicates a higher surface relative to that reservoir’s reference; a negative number indicates a lower one.
| Lake | Reading date | 7-day change | Conservation full |
|---|---|---|---|
| Lake Travis | 2026-09-28 | -0.80 ft | 89.6% |
| Canyon Lake | 2026-09-28 | -0.30 ft | 97.9% |
| Lake Corpus Christi | 2026-09-28 | -0.26 ft | 82.7% |
| Medina Lake | 2026-09-28 | -0.33 ft | 28.6% |
What is left out
This table does not identify the cause of a change. Rainfall, releases, withdrawals and measurement revisions require additional evidence. It also does not compare total available water between differently sized reservoirs.
Reproduce the note
Open each lake page for the source CSV and history chart. Check the dates before repeating the subtraction. The snapshot retrieval time is 2026-09-29T01:45:15.047Z. Independent human expert review of this note remains pending.
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