COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-09-16 07:58 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-09-16 00:00 | 1280.43 | 2026-09-16 17:00 | 1282.02 |
| 2026-09-15 00:00 | 1280.74 | 2026-09-16 23:00 | 1282.13 |
| 2026-09-14 00:00 | 1280.33 | 2026-09-17 05:00 | 1282.23 |
| 2026-09-13 00:00 | 1279.96 | 2026-09-17 11:00 | 1282.34 |
| 2026-09-12 00:00 | 1279.49 | 2026-09-17 17:00 | 1282.45 |
| 2026-09-11 00:00 | 1279.14 | 2026-09-17 23:00 | 1282.56 |
| 2026-09-10 00:00 | 1278.77 | 2026-09-18 05:00 | 1282.68 |
| 2026-09-09 00:00 | 1278.44 | 2026-09-18 11:00 | 1282.79 |
| 2026-09-08 00:00 | 1278.19 | 2026-09-18 17:00 | 1282.91 |
| 2026-09-07 00:00 | 1277.76 | 2026-09-18 23:00 | 1283.02 |
| 2026-09-06 00:00 | 1277.43 | 2026-09-19 05:00 | 1283.11 |
| 2026-09-19 11:00 | 1283.18 | ||
| 2026-09-19 17:00 | 1283.23 | ||
| 2026-09-19 23:00 | 1283.29 | ||
| 2026-09-20 05:00 | 1283.34 | ||
| 2026-09-20 11:00 | 1283.39 | ||
| 2026-09-20 17:00 | 1283.44 | ||
| 2026-09-20 23:00 | 1283.48 | ||
| 2026-09-21 05:00 | 1283.56 | ||
| 2026-09-21 11:00 | 1283.65 | ||
| 2026-09-21 17:00 | 1283.75 | ||
| 2026-09-21 23:00 | 1283.84 | ||
| 2026-09-22 05:00 | 1283.94 | ||
| 2026-09-22 11:00 | 1284.05 | ||
| 2026-09-22 17:00 | 1284.16 | ||
| 2026-09-22 23:00 | 1284.28 | ||
| 2026-09-23 05:00 | 1284.4 | ||
| 2026-09-23 11:00 | 1284.52 | ||
| 2026-09-23 17:00 | 1284.65 | ||
| 2026-09-23 23:00 | 1284.77 | ||
| 2026-09-24 05:00 | 1284.88 | ||
| 2026-09-24 11:00 | 1285 | ||
| 2026-09-24 17:00 | 1285.11 | ||
| 2026-09-24 23:00 | 1285.22 | ||
| 2026-09-25 05:00 | 1285.33 | ||
| 2026-09-25 11:00 | 1285.43 | ||
| 2026-09-25 17:00 | 1285.53 | ||
| 2026-09-25 23:00 | 1285.63 | ||
| 2026-09-26 05:00 | 1285.73 | ||