COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-09-19 09:48 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-09-19 00:00 | 1282.65 | 2026-09-19 23:00 | 1283.22 |
| 2026-09-18 00:00 | 1282.26 | 2026-09-20 05:00 | 1283.29 |
| 2026-09-17 00:00 | 1281.94 | 2026-09-20 11:00 | 1283.37 |
| 2026-09-16 00:00 | 1280.43 | 2026-09-20 17:00 | 1283.45 |
| 2026-09-15 00:00 | 1280.74 | 2026-09-20 23:00 | 1283.53 |
| 2026-09-14 00:00 | 1280.33 | 2026-09-21 05:00 | 1283.65 |
| 2026-09-13 00:00 | 1279.96 | 2026-09-21 11:00 | 1283.79 |
| 2026-09-12 00:00 | 1279.49 | 2026-09-21 17:00 | 1283.93 |
| 2026-09-11 00:00 | 1279.14 | 2026-09-21 23:00 | 1284.07 |
| 2026-09-10 00:00 | 1278.77 | 2026-09-22 05:00 | 1284.21 |
| 2026-09-09 00:00 | 1278.44 | 2026-09-22 11:00 | 1284.35 |
| 2026-09-22 17:00 | 1284.48 | ||
| 2026-09-22 23:00 | 1284.62 | ||
| 2026-09-23 05:00 | 1284.75 | ||
| 2026-09-23 11:00 | 1284.88 | ||
| 2026-09-23 17:00 | 1285.01 | ||
| 2026-09-23 23:00 | 1285.13 | ||
| 2026-09-24 05:00 | 1285.25 | ||
| 2026-09-24 11:00 | 1285.37 | ||
| 2026-09-24 17:00 | 1285.48 | ||
| 2026-09-24 23:00 | 1285.6 | ||
| 2026-09-25 05:00 | 1285.71 | ||
| 2026-09-25 11:00 | 1285.82 | ||
| 2026-09-25 17:00 | 1285.93 | ||
| 2026-09-25 23:00 | 1286.03 | ||
| 2026-09-26 05:00 | 1286.14 | ||
| 2026-09-26 11:00 | 1286.23 | ||
| 2026-09-26 17:00 | 1286.32 | ||
| 2026-09-26 23:00 | 1286.39 | ||
| 2026-09-27 05:00 | 1286.45 | ||
| 2026-09-27 11:00 | 1286.51 | ||
| 2026-09-27 17:00 | 1286.56 | ||
| 2026-09-27 23:00 | 1286.62 | ||
| 2026-09-28 05:00 | 1286.67 | ||
| 2026-09-28 11:00 | 1286.72 | ||
| 2026-09-28 17:00 | 1286.77 | ||
| 2026-09-28 23:00 | 1286.81 | ||
| 2026-09-29 05:00 | 1286.86 | ||