Table 8.1-2 IBI Score Descriptions
Rating |
Score Range |
Description |
---|---|---|
Good |
4.0-5.0 |
Comparable to reference streams considered to be minimally impacted. On average, metrics fall within the upper 50 percent of reference site conditions. |
Fair |
3.0-3.9 |
Comparable to reference conditions, but some aspects of biological integrity may not resemble the qualities of minimally impacted streams. On average, biological metrics are within the lower range of reference sites (10th to 50th percentile). |
Poor |
2.0-2.9 |
Significant deviation from reference conditions, with many aspects of biological integrity not resembling the qualities of minimally impacted streams, indicating some degradation. On average, biological metrics fall below the 10th percentile of reference site values. |
Very Poor |
1.0-1.9 |
Strong deviation from reference site conditions, with most aspects of biological integrity not resembling the qualities of minimally impacted streams, indicating severe degradation. On average, biological metrics fall below the 10th percentile of reference site values; most or all metrics are below this level. |