Macroinvertebrate Bioassessment Indices

NAMC uses observed to expected (O/E) and multimetric (MMI) indices to assess the biological condition of streams and rivers. We calculate both state-specific index and region-specific index scores as appropriate.

The state specific indices NAMC can apply include the following:

  1. Arizona Warm and Cold Water Indices of Biological Integrity
  2. Colorado Multimetric Index (all three biotypes)
  3. California Stream Condition Index
  4. Oregon Predator indices:
    1. Marine Western Coastal Forest
    2. Western Cordillera and Columbia Plateau
    3. Northern Basin and Range
  5. Utah Observed to Expected Index
  6. Wyoming Observed to Expected Index (all eleven bioregions)
  7. Nevada Multimetric Index (not used for regulatory purposes by the state)