COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-05-23 10:33 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-05-24 00:00 | 1265.46 | 2026-05-24 05:00 | 1265.66 |
| 2026-05-23 00:00 | 1264.92 | 2026-05-24 11:00 | 1265.81 |
| 2026-05-22 00:00 | 1264.36 | 2026-05-24 17:00 | 1265.97 |
| 2026-05-21 00:00 | 1263.6 | 2026-05-24 23:00 | 1266.13 |
| 2026-05-20 00:00 | 1262.87 | 2026-05-25 05:00 | 1266.28 |
| 2026-05-19 00:00 | 1262.35 | 2026-05-25 11:00 | 1266.44 |
| 2026-05-18 00:00 | 1261.14 | 2026-05-25 17:00 | 1266.59 |
| 2026-05-17 00:00 | 1259.44 | 2026-05-25 23:00 | 1266.75 |
| 2026-05-16 00:00 | 1258.22 | 2026-05-26 05:00 | 1266.91 |
| 2026-05-15 00:00 | 1257.07 | 2026-05-26 11:00 | 1267.07 |
| 2026-05-14 00:00 | 1256.2 | 2026-05-26 17:00 | 1267.23 |
| 2026-05-26 23:00 | 1267.4 | ||
| 2026-05-27 05:00 | 1267.56 | ||
| 2026-05-27 11:00 | 1267.73 | ||
| 2026-05-27 17:00 | 1267.91 | ||
| 2026-05-27 23:00 | 1268.09 | ||
| 2026-05-28 05:00 | 1268.27 | ||
| 2026-05-28 11:00 | 1268.46 | ||
| 2026-05-28 17:00 | 1268.65 | ||
| 2026-05-28 23:00 | 1268.84 | ||
| 2026-05-29 05:00 | 1269.03 | ||
| 2026-05-29 11:00 | 1269.22 | ||
| 2026-05-29 17:00 | 1269.41 | ||
| 2026-05-29 23:00 | 1269.59 | ||
| 2026-05-30 05:00 | 1269.77 | ||
| 2026-05-30 11:00 | 1269.95 | ||
| 2026-05-30 17:00 | 1270.12 | ||
| 2026-05-30 23:00 | 1270.29 | ||
| 2026-05-31 05:00 | 1270.46 | ||
| 2026-05-31 11:00 | 1270.62 | ||
| 2026-05-31 17:00 | 1270.78 | ||
| 2026-05-31 23:00 | 1270.93 | ||
| 2026-06-01 05:00 | 1271.09 | ||
| 2026-06-01 11:00 | 1271.25 | ||
| 2026-06-01 17:00 | 1271.41 | ||
| 2026-06-01 23:00 | 1271.57 | ||
| 2026-06-02 05:00 | 1271.72 | ||