COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-08-22 09:26 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-08-23 00:00 | 1278.98 | 2026-08-23 11:00 | 1278.73 |
| 2026-08-22 00:00 | 1279.08 | 2026-08-23 17:00 | 1278.67 |
| 2026-08-21 00:00 | 1279.41 | 2026-08-23 23:00 | 1278.61 |
| 2026-08-20 00:00 | 1279.85 | 2026-08-24 05:00 | 1278.56 |
| 2026-08-19 00:00 | 1280.1 | 2026-08-24 11:00 | 1278.51 |
| 2026-08-18 00:00 | 1280.4 | 2026-08-24 17:00 | 1278.46 |
| 2026-08-17 00:00 | 1280.75 | 2026-08-24 23:00 | 1278.41 |
| 2026-08-16 00:00 | 1281.13 | 2026-08-25 05:00 | 1278.36 |
| 2026-08-15 00:00 | 1281.59 | 2026-08-25 11:00 | 1278.31 |
| 2026-08-14 00:00 | 1281.88 | 2026-08-25 17:00 | 1278.26 |
| 2026-08-13 00:00 | 1282.11 | 2026-08-25 23:00 | 1278.21 |
| 2026-08-26 05:00 | 1278.16 | ||
| 2026-08-26 11:00 | 1278.11 | ||
| 2026-08-26 17:00 | 1278.06 | ||
| 2026-08-26 23:00 | 1278.01 | ||
| 2026-08-27 05:00 | 1277.96 | ||
| 2026-08-27 11:00 | 1277.91 | ||
| 2026-08-27 17:00 | 1277.86 | ||
| 2026-08-27 23:00 | 1277.81 | ||
| 2026-08-28 05:00 | 1277.76 | ||
| 2026-08-28 11:00 | 1277.71 | ||
| 2026-08-28 17:00 | 1277.66 | ||
| 2026-08-28 23:00 | 1277.61 | ||
| 2026-08-29 05:00 | 1277.56 | ||
| 2026-08-29 11:00 | 1277.5 | ||
| 2026-08-29 17:00 | 1277.45 | ||
| 2026-08-29 23:00 | 1277.4 | ||
| 2026-08-30 05:00 | 1277.35 | ||
| 2026-08-30 11:00 | 1277.3 | ||
| 2026-08-30 17:00 | 1277.25 | ||
| 2026-08-30 23:00 | 1277.2 | ||
| 2026-08-31 05:00 | 1277.15 | ||
| 2026-08-31 11:00 | 1277.1 | ||
| 2026-08-31 17:00 | 1277.05 | ||
| 2026-08-31 23:00 | 1277 | ||
| 2026-09-01 05:00 | 1277.02 | ||