COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-08-29 09:10 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-08-30 00:00 | 1277.4 | 2026-08-30 11:00 | 1277.27 |
| 2026-08-29 00:00 | 1277.27 | 2026-08-30 17:00 | 1277.23 |
| 2026-08-28 00:00 | 1277.34 | 2026-08-30 23:00 | 1277.18 |
| 2026-08-27 00:00 | 1277.72 | 2026-08-31 05:00 | 1277.14 |
| 2026-08-26 00:00 | 1278.3 | 2026-08-31 11:00 | 1277.09 |
| 2026-08-25 00:00 | 1278.7 | 2026-08-31 17:00 | 1277.05 |
| 2026-08-24 00:00 | 1278.99 | 2026-08-31 23:00 | 1277 |
| 2026-08-23 00:00 | 1278.98 | 2026-09-01 05:00 | 1277.05 |
| 2026-08-22 00:00 | 1279.08 | 2026-09-01 11:00 | 1277.19 |
| 2026-08-21 00:00 | 1279.41 | 2026-09-01 17:00 | 1277.33 |
| 2026-08-20 00:00 | 1279.85 | 2026-09-01 23:00 | 1277.47 |
| 2026-09-02 05:00 | 1277.62 | ||
| 2026-09-02 11:00 | 1277.76 | ||
| 2026-09-02 17:00 | 1277.91 | ||
| 2026-09-02 23:00 | 1278.06 | ||
| 2026-09-03 05:00 | 1278.19 | ||
| 2026-09-03 11:00 | 1278.32 | ||
| 2026-09-03 17:00 | 1278.44 | ||
| 2026-09-03 23:00 | 1278.57 | ||
| 2026-09-04 05:00 | 1278.69 | ||
| 2026-09-04 11:00 | 1278.82 | ||
| 2026-09-04 17:00 | 1278.95 | ||
| 2026-09-04 23:00 | 1279.08 | ||
| 2026-09-05 05:00 | 1279.21 | ||
| 2026-09-05 11:00 | 1279.34 | ||
| 2026-09-05 17:00 | 1279.47 | ||
| 2026-09-05 23:00 | 1279.6 | ||
| 2026-09-06 05:00 | 1279.74 | ||
| 2026-09-06 11:00 | 1279.87 | ||
| 2026-09-06 17:00 | 1280 | ||
| 2026-09-06 23:00 | 1280.13 | ||
| 2026-09-07 05:00 | 1280.26 | ||
| 2026-09-07 11:00 | 1280.38 | ||
| 2026-09-07 17:00 | 1280.5 | ||
| 2026-09-07 23:00 | 1280.61 | ||
| 2026-09-08 05:00 | 1280.72 | ||