COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-07-29 08:14 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-07-29 00:00 | 1285.89 | 2026-07-29 23:00 | 1285.5 |
| 2026-07-28 00:00 | 1286.37 | 2026-07-30 05:00 | 1285.4 |
| 2026-07-27 00:00 | 1286.63 | 2026-07-30 11:00 | 1285.31 |
| 2026-07-26 00:00 | 1286.83 | 2026-07-30 17:00 | 1285.21 |
| 2026-07-25 00:00 | 1287.5 | 2026-07-30 23:00 | 1285.11 |
| 2026-07-24 00:00 | 1287.9 | 2026-07-31 05:00 | 1285.01 |
| 2026-07-23 00:00 | 1288.07 | 2026-07-31 11:00 | 1284.9 |
| 2026-07-22 00:00 | 1288.42 | 2026-07-31 17:00 | 1284.79 |
| 2026-07-21 00:00 | 1288.46 | 2026-07-31 23:00 | 1284.68 |
| 2026-07-20 00:00 | 1288.58 | 2026-08-01 05:00 | 1284.57 |
| 2026-07-19 00:00 | 1288.69 | 2026-08-01 11:00 | 1284.47 |
| 2026-08-01 17:00 | 1284.37 | ||
| 2026-08-01 23:00 | 1284.27 | ||
| 2026-08-02 05:00 | 1284.17 | ||
| 2026-08-02 11:00 | 1284.07 | ||
| 2026-08-02 17:00 | 1283.98 | ||
| 2026-08-02 23:00 | 1283.88 | ||
| 2026-08-03 05:00 | 1283.78 | ||
| 2026-08-03 11:00 | 1283.68 | ||
| 2026-08-03 17:00 | 1283.58 | ||
| 2026-08-03 23:00 | 1283.48 | ||
| 2026-08-04 05:00 | 1283.37 | ||
| 2026-08-04 11:00 | 1283.27 | ||
| 2026-08-04 17:00 | 1283.17 | ||
| 2026-08-04 23:00 | 1283.06 | ||
| 2026-08-05 05:00 | 1282.96 | ||
| 2026-08-05 11:00 | 1282.85 | ||
| 2026-08-05 17:00 | 1282.75 | ||
| 2026-08-05 23:00 | 1282.64 | ||
| 2026-08-06 05:00 | 1282.54 | ||
| 2026-08-06 11:00 | 1282.43 | ||
| 2026-08-06 17:00 | 1282.32 | ||
| 2026-08-06 23:00 | 1282.22 | ||
| 2026-08-07 05:00 | 1282.11 | ||
| 2026-08-07 11:00 | 1282 | ||
| 2026-08-07 17:00 | 1281.9 | ||
| 2026-08-07 23:00 | 1281.79 | ||
| 2026-08-08 05:00 | 1281.68 | ||