| Code | Description |
| Temporarily Flooded | Surface water is present for brief periods during the growing season, but the water table usually lies well below the soil surface for most of the season. Plants that grow both in uplands and wetlands are characteristic of the temporarily flooded regime. |
| Saturated | The substrate is saturated to the surface for extended periods during the growing season, but surface water is seldom present. |
| Seasonally Flooded | Surface water is present for extended periods especially early in the growing season, but is absent by the end of the season in most years. When surface water is absent, the water table is often near the land surface. |
| Seasonal/well-drained | |
| Seasonal/saturated | During a seasonal period, the ground is incapable of holding more water. |
| Semipermanently Flooded | Surface water persists throughout the growing season in most years. When surface water is absent, the water table is usually at or very near the land surface. |
| Intermittently Exposed | Surface water is present throughout the year except in years of extreme drought. |
| Permanently Flooded | Water covers the land surface throughout the year in all years. Vegetation is composed of obligate hydrophytes. |
| Intermittently Flooded | The substrate is usually exposed, but surface water is present for variable periods without detectable seasonal periodicity. |
| Artificially Flooded | The amount and duration of flooding is controlled by means of pumps or siphons in combination with dikes or dams. The vegetation growing on these areas cannot be considered a reliable indicator of water regime. |
| Unknown | |
| Intermittently Flooded/Temporary | |
| Saturated/Semipermanent/Seasonal | |
| Intermittently Exposed/Permanent | |
