COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-08-04 09:59 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-08-04 00:00 | 1284.21 | 2026-08-05 05:00 | 1283.8 |
| 2026-08-03 00:00 | 1284.36 | 2026-08-05 11:00 | 1283.71 |
| 2026-08-02 00:00 | 1284.44 | 2026-08-05 17:00 | 1283.63 |
| 2026-08-01 00:00 | 1285.01 | 2026-08-05 23:00 | 1283.54 |
| 2026-07-31 00:00 | 1285.45 | 2026-08-06 05:00 | 1283.45 |
| 2026-07-30 00:00 | 1285.69 | 2026-08-06 11:00 | 1283.37 |
| 2026-07-29 00:00 | 1285.89 | 2026-08-06 17:00 | 1283.28 |
| 2026-07-28 00:00 | 1286.37 | 2026-08-06 23:00 | 1283.2 |
| 2026-07-27 00:00 | 1286.63 | 2026-08-07 05:00 | 1283.11 |
| 2026-07-26 00:00 | 1286.83 | 2026-08-07 11:00 | 1283.03 |
| 2026-07-25 00:00 | 1287.5 | 2026-08-07 17:00 | 1282.96 |
| 2026-08-07 23:00 | 1282.88 | ||
| 2026-08-08 05:00 | 1282.81 | ||
| 2026-08-08 11:00 | 1282.73 | ||
| 2026-08-08 17:00 | 1282.66 | ||
| 2026-08-08 23:00 | 1282.58 | ||
| 2026-08-09 05:00 | 1282.5 | ||
| 2026-08-09 11:00 | 1282.43 | ||
| 2026-08-09 17:00 | 1282.35 | ||
| 2026-08-09 23:00 | 1282.27 | ||
| 2026-08-10 05:00 | 1282.2 | ||
| 2026-08-10 11:00 | 1282.13 | ||
| 2026-08-10 17:00 | 1282.05 | ||
| 2026-08-10 23:00 | 1281.98 | ||
| 2026-08-11 05:00 | 1281.91 | ||
| 2026-08-11 11:00 | 1281.84 | ||
| 2026-08-11 17:00 | 1281.76 | ||
| 2026-08-11 23:00 | 1281.69 | ||
| 2026-08-12 05:00 | 1281.62 | ||
| 2026-08-12 11:00 | 1281.56 | ||
| 2026-08-12 17:00 | 1281.49 | ||
| 2026-08-12 23:00 | 1281.42 | ||
| 2026-08-13 05:00 | 1281.35 | ||
| 2026-08-13 11:00 | 1281.29 | ||
| 2026-08-13 17:00 | 1281.22 | ||
| 2026-08-13 23:00 | 1281.16 | ||
| 2026-08-14 05:00 | 1281.09 | ||