COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-09-13 08:53 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-09-13 00:00 | 1279.96 | 2026-09-13 11:00 | 1280.42 |
| 2026-09-12 00:00 | 1279.49 | 2026-09-13 17:00 | 1280.51 |
| 2026-09-11 00:00 | 1279.14 | 2026-09-13 23:00 | 1280.6 |
| 2026-09-10 00:00 | 1278.77 | 2026-09-14 05:00 | 1280.71 |
| 2026-09-09 00:00 | 1278.44 | 2026-09-14 11:00 | 1280.84 |
| 2026-09-08 00:00 | 1278.19 | 2026-09-14 17:00 | 1280.96 |
| 2026-09-07 00:00 | 1277.76 | 2026-09-14 23:00 | 1281.08 |
| 2026-09-06 00:00 | 1277.43 | 2026-09-15 05:00 | 1281.2 |
| 2026-09-05 00:00 | 1277.17 | 2026-09-15 11:00 | 1281.31 |
| 2026-09-04 00:00 | 1276.76 | 2026-09-15 17:00 | 1281.43 |
| 2026-09-03 00:00 | 1276.64 | 2026-09-15 23:00 | 1281.54 |
| 2026-09-16 05:00 | 1281.66 | ||
| 2026-09-16 11:00 | 1281.77 | ||
| 2026-09-16 17:00 | 1281.88 | ||
| 2026-09-16 23:00 | 1281.99 | ||
| 2026-09-17 05:00 | 1282.09 | ||
| 2026-09-17 11:00 | 1282.2 | ||
| 2026-09-17 17:00 | 1282.31 | ||
| 2026-09-17 23:00 | 1282.42 | ||
| 2026-09-18 05:00 | 1282.52 | ||
| 2026-09-18 11:00 | 1282.63 | ||
| 2026-09-18 17:00 | 1282.74 | ||
| 2026-09-18 23:00 | 1282.85 | ||
| 2026-09-19 05:00 | 1282.93 | ||
| 2026-09-19 11:00 | 1282.99 | ||
| 2026-09-19 17:00 | 1283.05 | ||
| 2026-09-19 23:00 | 1283.1 | ||
| 2026-09-20 05:00 | 1283.14 | ||
| 2026-09-20 11:00 | 1283.19 | ||
| 2026-09-20 17:00 | 1283.24 | ||
| 2026-09-20 23:00 | 1283.28 | ||
| 2026-09-21 05:00 | 1283.35 | ||
| 2026-09-21 11:00 | 1283.44 | ||
| 2026-09-21 17:00 | 1283.53 | ||
| 2026-09-21 23:00 | 1283.62 | ||
| 2026-09-22 05:00 | 1283.71 | ||
| 2026-09-22 11:00 | 1283.82 | ||
| 2026-09-22 17:00 | 1283.93 | ||
| 2026-09-22 23:00 | 1284.05 | ||
| 2026-09-23 05:00 | 1284.17 | ||