| Biotic Index | Water Quality | Degree of Organic Pollution |
| 0.00-3.50 | Excellent | No apparent organic pollution |
| 3.51-4.50 | Very good | Possible slight organic pollution |
| 4.51-5.50 | Good | Some organic pollution |
| 5.51-6.50 | Fair | Fairly significant organic pollution |
| 6.51-7.50 | Fairly poor | Significant organic pollution |
| 7.51-8.50 | Poor | Very significant organic pollution |
| 8.51-10.00 | Very poor | Severe organic pollution |