COLUMBIA--GRAND COULEE DAM (GCDW1)
| Observed | Forecast/Trend Issued: 2026-05-31 09:31 PDT | ||
| Date/Time (PDT) | Pool Height | Date/Time (PDT) | Pool Height |
| 2026-05-31 00:00 | 1271.93 | 2026-05-31 11:00 | 1273.47 |
| 2026-05-30 00:00 | 1270.22 | 2026-05-31 17:00 | 1273.76 |
| 2026-05-29 00:00 | 1269.38 | 2026-05-31 23:00 | 1274.06 |
| 2026-05-28 00:00 | 1268.89 | 2026-06-01 05:00 | 1274.37 |
| 2026-05-27 00:00 | 1268.13 | 2026-06-01 11:00 | 1274.69 |
| 2026-05-26 00:00 | 1267.39 | 2026-06-01 17:00 | 1275.03 |
| 2026-05-25 00:00 | 1266.66 | 2026-06-01 23:00 | 1275.37 |
| 2026-05-24 00:00 | 1265.46 | 2026-06-02 05:00 | 1275.72 |
| 2026-05-23 00:00 | 1264.92 | 2026-06-02 11:00 | 1276.08 |
| 2026-05-22 00:00 | 1264.36 | 2026-06-02 17:00 | 1276.44 |
| 2026-05-21 00:00 | 1263.6 | 2026-06-02 23:00 | 1276.79 |
| 2026-06-03 05:00 | 1277.14 | ||
| 2026-06-03 11:00 | 1277.47 | ||
| 2026-06-03 17:00 | 1277.8 | ||
| 2026-06-03 23:00 | 1278.12 | ||
| 2026-06-04 05:00 | 1278.43 | ||
| 2026-06-04 11:00 | 1278.72 | ||
| 2026-06-04 17:00 | 1279 | ||
| 2026-06-04 23:00 | 1279.26 | ||
| 2026-06-05 05:00 | 1279.49 | ||
| 2026-06-05 11:00 | 1279.71 | ||
| 2026-06-05 17:00 | 1279.91 | ||
| 2026-06-05 23:00 | 1280.09 | ||
| 2026-06-06 05:00 | 1280.26 | ||
| 2026-06-06 11:00 | 1280.42 | ||
| 2026-06-06 17:00 | 1280.58 | ||
| 2026-06-06 23:00 | 1280.75 | ||
| 2026-06-07 05:00 | 1280.91 | ||
| 2026-06-07 11:00 | 1281.06 | ||
| 2026-06-07 17:00 | 1281.21 | ||
| 2026-06-07 23:00 | 1281.35 | ||
| 2026-06-08 05:00 | 1281.49 | ||
| 2026-06-08 11:00 | 1281.62 | ||
| 2026-06-08 17:00 | 1281.75 | ||
| 2026-06-08 23:00 | 1281.88 | ||
| 2026-06-09 05:00 | 1281.99 | ||
| 2026-06-09 11:00 | 1282.1 | ||
| 2026-06-09 17:00 | 1282.2 | ||
| 2026-06-09 23:00 | 1282.3 | ||
| 2026-06-10 05:00 | 1282.38 | ||