COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-08-31 10:29 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-09-01 00:00 | 1277.43 | 2026-09-01 11:00 | 1277.06 |
| 2026-08-31 00:00 | 1277.5 | 2026-09-01 17:00 | 1277.18 |
| 2026-08-30 00:00 | 1277.4 | 2026-09-01 23:00 | 1277.31 |
| 2026-08-29 00:00 | 1277.27 | 2026-09-02 05:00 | 1277.43 |
| 2026-08-28 00:00 | 1277.34 | 2026-09-02 11:00 | 1277.56 |
| 2026-08-27 00:00 | 1277.72 | 2026-09-02 17:00 | 1277.68 |
| 2026-08-26 00:00 | 1278.3 | 2026-09-02 23:00 | 1277.81 |
| 2026-08-25 00:00 | 1278.7 | 2026-09-03 05:00 | 1277.93 |
| 2026-08-24 00:00 | 1278.99 | 2026-09-03 11:00 | 1278.04 |
| 2026-08-23 00:00 | 1278.98 | 2026-09-03 17:00 | 1278.15 |
| 2026-08-22 00:00 | 1279.08 | 2026-09-03 23:00 | 1278.26 |
| 2026-09-04 05:00 | 1278.37 | ||
| 2026-09-04 11:00 | 1278.48 | ||
| 2026-09-04 17:00 | 1278.6 | ||
| 2026-09-04 23:00 | 1278.71 | ||
| 2026-09-05 05:00 | 1278.83 | ||
| 2026-09-05 11:00 | 1278.95 | ||
| 2026-09-05 17:00 | 1279.06 | ||
| 2026-09-05 23:00 | 1279.16 | ||
| 2026-09-06 05:00 | 1279.26 | ||
| 2026-09-06 11:00 | 1279.36 | ||
| 2026-09-06 17:00 | 1279.46 | ||
| 2026-09-06 23:00 | 1279.56 | ||
| 2026-09-07 05:00 | 1279.66 | ||
| 2026-09-07 11:00 | 1279.76 | ||
| 2026-09-07 17:00 | 1279.85 | ||
| 2026-09-07 23:00 | 1279.95 | ||
| 2026-09-08 05:00 | 1280.04 | ||
| 2026-09-08 11:00 | 1280.13 | ||
| 2026-09-08 17:00 | 1280.22 | ||
| 2026-09-08 23:00 | 1280.31 | ||
| 2026-09-09 05:00 | 1280.4 | ||
| 2026-09-09 11:00 | 1280.49 | ||
| 2026-09-09 17:00 | 1280.59 | ||
| 2026-09-09 23:00 | 1280.68 | ||
| 2026-09-10 05:00 | 1280.78 | ||