COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-09-25 08:13 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-09-25 00:00 | 1284.81 | 2026-09-25 23:00 | 1285.15 |
| 2026-09-24 00:00 | 1284.55 | 2026-09-26 05:00 | 1285.19 |
| 2026-09-23 00:00 | 1284.08 | 2026-09-26 11:00 | 1285.22 |
| 2026-09-22 00:00 | 1283.63 | 2026-09-26 17:00 | 1285.25 |
| 2026-09-21 00:00 | 1283.33 | 2026-09-26 23:00 | 1285.28 |
| 2026-09-20 00:00 | 1283.11 | 2026-09-27 05:00 | 1285.3 |
| 2026-09-19 00:00 | 1282.65 | 2026-09-27 11:00 | 1285.3 |
| 2026-09-18 00:00 | 1282.26 | 2026-09-27 17:00 | 1285.29 |
| 2026-09-17 00:00 | 1281.94 | 2026-09-27 23:00 | 1285.29 |
| 2026-09-16 00:00 | 1280.43 | 2026-09-28 05:00 | 1285.31 |
| 2026-09-15 00:00 | 1280.74 | 2026-09-28 11:00 | 1285.36 |
| 2026-09-28 17:00 | 1285.4 | ||
| 2026-09-28 23:00 | 1285.44 | ||
| 2026-09-29 05:00 | 1285.48 | ||
| 2026-09-29 11:00 | 1285.52 | ||
| 2026-09-29 17:00 | 1285.54 | ||
| 2026-09-29 23:00 | 1285.55 | ||
| 2026-09-30 05:00 | 1285.54 | ||
| 2026-09-30 11:00 | 1285.53 | ||
| 2026-09-30 17:00 | 1285.51 | ||
| 2026-09-30 23:00 | 1285.5 | ||
| 2026-10-01 05:00 | 1285.52 | ||
| 2026-10-01 11:00 | 1285.54 | ||
| 2026-10-01 17:00 | 1285.56 | ||
| 2026-10-01 23:00 | 1285.58 | ||
| 2026-10-02 05:00 | 1285.6 | ||
| 2026-10-02 11:00 | 1285.62 | ||
| 2026-10-02 17:00 | 1285.64 | ||
| 2026-10-02 23:00 | 1285.66 | ||
| 2026-10-03 05:00 | 1285.68 | ||
| 2026-10-03 11:00 | 1285.7 | ||
| 2026-10-03 17:00 | 1285.72 | ||
| 2026-10-03 23:00 | 1285.74 | ||
| 2026-10-04 05:00 | 1285.76 | ||
| 2026-10-04 11:00 | 1285.78 | ||
| 2026-10-04 17:00 | 1285.8 | ||
| 2026-10-04 23:00 | 1285.82 | ||
| 2026-10-05 05:00 | 1285.84 | ||