COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-08-13 09:30 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-08-14 00:00 | 1281.88 | 2026-08-14 05:00 | 1281.68 |
| 2026-08-13 00:00 | 1282.11 | 2026-08-14 11:00 | 1281.59 |
| 2026-08-12 00:00 | 1282.46 | 2026-08-14 17:00 | 1281.5 |
| 2026-08-11 00:00 | 1282.75 | 2026-08-14 23:00 | 1281.4 |
| 2026-08-10 00:00 | 1282.83 | 2026-08-15 05:00 | 1281.29 |
| 2026-08-09 00:00 | 1283 | 2026-08-15 11:00 | 1281.19 |
| 2026-08-08 00:00 | 1283.34 | 2026-08-15 17:00 | 1281.07 |
| 2026-08-07 00:00 | 1283.62 | 2026-08-15 23:00 | 1280.96 |
| 2026-08-06 00:00 | 1283.81 | 2026-08-16 05:00 | 1280.84 |
| 2026-08-05 00:00 | 1284.03 | 2026-08-16 11:00 | 1280.73 |
| 2026-08-04 00:00 | 1284.21 | 2026-08-16 17:00 | 1280.62 |
| 2026-08-16 23:00 | 1280.51 | ||
| 2026-08-17 05:00 | 1280.4 | ||
| 2026-08-17 11:00 | 1280.29 | ||
| 2026-08-17 17:00 | 1280.18 | ||
| 2026-08-17 23:00 | 1280.08 | ||
| 2026-08-18 05:00 | 1279.97 | ||
| 2026-08-18 11:00 | 1279.86 | ||
| 2026-08-18 17:00 | 1279.76 | ||
| 2026-08-18 23:00 | 1279.66 | ||
| 2026-08-19 05:00 | 1279.56 | ||
| 2026-08-19 11:00 | 1279.46 | ||
| 2026-08-19 17:00 | 1279.36 | ||
| 2026-08-19 23:00 | 1279.26 | ||
| 2026-08-20 05:00 | 1279.16 | ||
| 2026-08-20 11:00 | 1279.06 | ||
| 2026-08-20 17:00 | 1278.96 | ||
| 2026-08-20 23:00 | 1278.86 | ||
| 2026-08-21 05:00 | 1278.76 | ||
| 2026-08-21 11:00 | 1278.66 | ||
| 2026-08-21 17:00 | 1278.56 | ||
| 2026-08-21 23:00 | 1278.46 | ||
| 2026-08-22 05:00 | 1278.35 | ||
| 2026-08-22 11:00 | 1278.25 | ||
| 2026-08-22 17:00 | 1278.15 | ||
| 2026-08-22 23:00 | 1278.05 | ||
| 2026-08-23 05:00 | 1277.95 | ||