COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-06-20 10:38 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-06-20 00:00 | 1282.98 | 2026-06-20 17:00 | 1283.45 |
| 2026-06-19 00:00 | 1282.95 | 2026-06-20 23:00 | 1283.52 |
| 2026-06-18 00:00 | 1282.21 | 2026-06-21 05:00 | 1283.59 |
| 2026-06-17 00:00 | 1281.32 | 2026-06-21 11:00 | 1283.67 |
| 2026-06-16 00:00 | 1281.16 | 2026-06-21 17:00 | 1283.72 |
| 2026-06-15 00:00 | 1281.43 | 2026-06-21 23:00 | 1283.77 |
| 2026-06-14 00:00 | 1281.55 | 2026-06-22 05:00 | 1283.83 |
| 2026-06-13 00:00 | 1281.58 | 2026-06-22 11:00 | 1283.88 |
| 2026-06-12 00:00 | 1281.06 | 2026-06-22 17:00 | 1283.94 |
| 2026-06-11 00:00 | 1280.08 | 2026-06-22 23:00 | 1283.99 |
| 2026-06-10 00:00 | 1278.74 | 2026-06-23 05:00 | 1284.05 |
| 2026-06-23 11:00 | 1284.1 | ||
| 2026-06-23 17:00 | 1284.15 | ||
| 2026-06-23 23:00 | 1284.21 | ||
| 2026-06-24 05:00 | 1284.26 | ||
| 2026-06-24 11:00 | 1284.32 | ||
| 2026-06-24 17:00 | 1284.37 | ||
| 2026-06-24 23:00 | 1284.43 | ||
| 2026-06-25 05:00 | 1284.48 | ||
| 2026-06-25 11:00 | 1284.53 | ||
| 2026-06-25 17:00 | 1284.59 | ||
| 2026-06-25 23:00 | 1284.64 | ||
| 2026-06-26 05:00 | 1284.7 | ||
| 2026-06-26 11:00 | 1284.75 | ||
| 2026-06-26 17:00 | 1284.81 | ||
| 2026-06-26 23:00 | 1284.86 | ||
| 2026-06-27 05:00 | 1284.91 | ||
| 2026-06-27 11:00 | 1284.97 | ||
| 2026-06-27 17:00 | 1285.02 | ||
| 2026-06-27 23:00 | 1285.08 | ||
| 2026-06-28 05:00 | 1285.13 | ||
| 2026-06-28 11:00 | 1285.19 | ||
| 2026-06-28 17:00 | 1285.24 | ||
| 2026-06-28 23:00 | 1285.3 | ||
| 2026-06-29 05:00 | 1285.35 | ||
| 2026-06-29 11:00 | 1285.4 | ||
| 2026-06-29 17:00 | 1285.46 | ||
| 2026-06-29 23:00 | 1285.51 | ||
| 2026-06-30 05:00 | 1285.57 | ||