COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-09-09 09:17 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-09-10 00:00 | 1278.77 | 2026-09-10 11:00 | 1278.97 |
| 2026-09-09 00:00 | 1278.44 | 2026-09-10 17:00 | 1279.05 |
| 2026-09-08 00:00 | 1278.19 | 2026-09-10 23:00 | 1279.14 |
| 2026-09-07 00:00 | 1277.76 | 2026-09-11 05:00 | 1279.22 |
| 2026-09-06 00:00 | 1277.43 | 2026-09-11 11:00 | 1279.3 |
| 2026-09-05 00:00 | 1277.17 | 2026-09-11 17:00 | 1279.38 |
| 2026-09-04 00:00 | 1276.76 | 2026-09-11 23:00 | 1279.44 |
| 2026-09-03 00:00 | 1276.64 | 2026-09-12 05:00 | 1279.5 |
| 2026-09-02 00:00 | 1276.78 | 2026-09-12 11:00 | 1279.56 |
| 2026-09-01 00:00 | 1277.43 | 2026-09-12 17:00 | 1279.61 |
| 2026-08-31 00:00 | 1277.5 | 2026-09-12 23:00 | 1279.66 |
| 2026-09-13 05:00 | 1279.71 | ||
| 2026-09-13 11:00 | 1279.76 | ||
| 2026-09-13 17:00 | 1279.81 | ||
| 2026-09-13 23:00 | 1279.85 | ||
| 2026-09-14 05:00 | 1279.92 | ||
| 2026-09-14 11:00 | 1280 | ||
| 2026-09-14 17:00 | 1280.07 | ||
| 2026-09-14 23:00 | 1280.15 | ||
| 2026-09-15 05:00 | 1280.23 | ||
| 2026-09-15 11:00 | 1280.32 | ||
| 2026-09-15 17:00 | 1280.4 | ||
| 2026-09-15 23:00 | 1280.48 | ||
| 2026-09-16 05:00 | 1280.56 | ||
| 2026-09-16 11:00 | 1280.64 | ||
| 2026-09-16 17:00 | 1280.73 | ||
| 2026-09-16 23:00 | 1280.81 | ||
| 2026-09-17 05:00 | 1280.89 | ||
| 2026-09-17 11:00 | 1280.97 | ||
| 2026-09-17 17:00 | 1281.06 | ||
| 2026-09-17 23:00 | 1281.14 | ||
| 2026-09-18 05:00 | 1281.22 | ||
| 2026-09-18 11:00 | 1281.3 | ||
| 2026-09-18 17:00 | 1281.38 | ||
| 2026-09-18 23:00 | 1281.46 | ||
| 2026-09-19 05:00 | 1281.53 | ||