COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-09-05 08:55 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-09-05 00:00 | 1277.17 | 2026-09-05 17:00 | 1277.59 |
| 2026-09-04 00:00 | 1276.76 | 2026-09-05 23:00 | 1277.67 |
| 2026-09-03 00:00 | 1276.64 | 2026-09-06 05:00 | 1277.75 |
| 2026-09-02 00:00 | 1276.78 | 2026-09-06 11:00 | 1277.81 |
| 2026-09-01 00:00 | 1277.43 | 2026-09-06 17:00 | 1277.88 |
| 2026-08-31 00:00 | 1277.5 | 2026-09-06 23:00 | 1277.94 |
| 2026-08-30 00:00 | 1277.4 | 2026-09-07 05:00 | 1278.01 |
| 2026-08-29 00:00 | 1277.27 | 2026-09-07 11:00 | 1278.1 |
| 2026-08-28 00:00 | 1277.34 | 2026-09-07 17:00 | 1278.19 |
| 2026-08-27 00:00 | 1277.72 | 2026-09-07 23:00 | 1278.27 |
| 2026-08-26 00:00 | 1278.3 | 2026-09-08 05:00 | 1278.35 |
| 2026-09-08 11:00 | 1278.43 | ||
| 2026-09-08 17:00 | 1278.51 | ||
| 2026-09-08 23:00 | 1278.59 | ||
| 2026-09-09 05:00 | 1278.67 | ||
| 2026-09-09 11:00 | 1278.75 | ||
| 2026-09-09 17:00 | 1278.83 | ||
| 2026-09-09 23:00 | 1278.91 | ||
| 2026-09-10 05:00 | 1278.98 | ||
| 2026-09-10 11:00 | 1279.06 | ||
| 2026-09-10 17:00 | 1279.14 | ||
| 2026-09-10 23:00 | 1279.21 | ||
| 2026-09-11 05:00 | 1279.28 | ||
| 2026-09-11 11:00 | 1279.35 | ||
| 2026-09-11 17:00 | 1279.41 | ||
| 2026-09-11 23:00 | 1279.46 | ||
| 2026-09-12 05:00 | 1279.51 | ||
| 2026-09-12 11:00 | 1279.55 | ||
| 2026-09-12 17:00 | 1279.6 | ||
| 2026-09-12 23:00 | 1279.65 | ||
| 2026-09-13 05:00 | 1279.69 | ||
| 2026-09-13 11:00 | 1279.73 | ||
| 2026-09-13 17:00 | 1279.78 | ||
| 2026-09-13 23:00 | 1279.82 | ||
| 2026-09-14 05:00 | 1279.88 | ||
| 2026-09-14 11:00 | 1279.95 | ||
| 2026-09-14 17:00 | 1280.02 | ||
| 2026-09-14 23:00 | 1280.09 | ||
| 2026-09-15 05:00 | 1280.16 | ||