COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-08-07 09:45 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-08-08 00:00 | 1283.34 | 2026-08-08 11:00 | 1283.09 |
| 2026-08-07 00:00 | 1283.62 | 2026-08-08 17:00 | 1283.02 |
| 2026-08-06 00:00 | 1283.81 | 2026-08-08 23:00 | 1282.95 |
| 2026-08-05 00:00 | 1284.03 | 2026-08-09 05:00 | 1282.88 |
| 2026-08-04 00:00 | 1284.21 | 2026-08-09 11:00 | 1282.81 |
| 2026-08-03 00:00 | 1284.36 | 2026-08-09 17:00 | 1282.75 |
| 2026-08-02 00:00 | 1284.44 | 2026-08-09 23:00 | 1282.69 |
| 2026-08-01 00:00 | 1285.01 | 2026-08-10 05:00 | 1282.62 |
| 2026-07-31 00:00 | 1285.45 | 2026-08-10 11:00 | 1282.56 |
| 2026-07-30 00:00 | 1285.69 | 2026-08-10 17:00 | 1282.49 |
| 2026-07-29 00:00 | 1285.89 | 2026-08-10 23:00 | 1282.42 |
| 2026-08-11 05:00 | 1282.35 | ||
| 2026-08-11 11:00 | 1282.28 | ||
| 2026-08-11 17:00 | 1282.21 | ||
| 2026-08-11 23:00 | 1282.13 | ||
| 2026-08-12 05:00 | 1282.06 | ||
| 2026-08-12 11:00 | 1281.98 | ||
| 2026-08-12 17:00 | 1281.91 | ||
| 2026-08-12 23:00 | 1281.84 | ||
| 2026-08-13 05:00 | 1281.76 | ||
| 2026-08-13 11:00 | 1281.69 | ||
| 2026-08-13 17:00 | 1281.61 | ||
| 2026-08-13 23:00 | 1281.54 | ||
| 2026-08-14 05:00 | 1281.46 | ||
| 2026-08-14 11:00 | 1281.39 | ||
| 2026-08-14 17:00 | 1281.31 | ||
| 2026-08-14 23:00 | 1281.23 | ||
| 2026-08-15 05:00 | 1281.15 | ||
| 2026-08-15 11:00 | 1281.07 | ||
| 2026-08-15 17:00 | 1280.99 | ||
| 2026-08-15 23:00 | 1280.91 | ||
| 2026-08-16 05:00 | 1280.83 | ||
| 2026-08-16 11:00 | 1280.75 | ||
| 2026-08-16 17:00 | 1280.67 | ||
| 2026-08-16 23:00 | 1280.59 | ||
| 2026-08-17 05:00 | 1280.52 | ||