| RANK | WQI VALUE | DESCRIPTION |
| Excellent | 95 - 100 | Water quality very close to natural or pristine levels. |
| Very Good | 89 - 94 | Water quality close to natural pristine levels. |
| Good | 80 - 88 | Water quality condition rarely departs from natural or pristine levels. |
| Fair | 65 - 79 | Water quality sometimes departs from natural or desirable levels. |
| Marginal | 45 - 64 | Water quality conditions often depart from natural or desirable levels. |
| Poor | 0 - 44 | Water quality conditions usually depart from natural or desirable levels. |