Arizona

Arizona has two different perennial MMIs used in state standard biocriteria: cold water for sites above 5000 foot elevation, and warm water for sites below this elevation. Tetra Tech, Inc. developed both MMIs in 2000 and 2006. To calculate the MMIs, macroinvertebrates should be identified to NAMC’s standard taxonomic resolution and collected May 1 - June 1 for the cold water MMI and April 1-May 1 for the warm water MMI. The index is calculated using an access database rather than using NAMC’s automated R scripts and therefore requires an additional cost compared to other indices.

Arizona has two different perennial indices: cold water for sites above 5000 foot elevation, and warm water for sites below this elevation.

Index # Reference Sites # Degraded Sites Index Mean Index SD Moderate departure from reference benchmark Major departure from reference benchmark Narrative conditions
Cold Water 30 9 58 13 < 52 < 45 Meeting, Inconclusive, Violating
Warm Water 33 17 57 15 < 50 < 39 Meeting, Inconclusive, Violating

State of Arizona with blue and red dots corresponding to cold and warm water
Arizona macroinvertebrate reference sites for the cold water (blue) and warm water (red) indices.

Warm Water

Box plots of catch elevation(m) on a scale of 600 to 1800 with a mean of 1300, mean annual precipitation (mm) on a scale of 300 to 800 with a mean of 25250, temperature (C) on a scale of 5 to 20 with a mean of 14 and log watershed area (km2) on a scale of 1 to 4 with a mean of 2.5
Environmental gradients of reference sites used to develop Arizona perennial warm water MMI and used for NAMC’s model applicability test

  • Method for accounting for natural environmental gradients: Elevation category and reference site selection criteria
  • Predictors of reference assemblages or metrics: none
  • Metrics used
    • total richness
    • # Trichoptera taxa
    • # Ephemeroptera taxa
    • # Diptera taxa
    • # scraper taxa, % scraper
    • % Ephemeroptera
    • % Dominant Taxon
    • Hilsenhoff Biotic Index
  • Fixed count: 500
  • Minimum count: unspecified
  • Operational Taxonomic Unit (OTU) applied: No
  • Rare taxa <0.5 probability of capture included: Yes
  • Documentation

Cold Water

Box plots of catch elevation(m) on a scale of 1700 to 3000 with a mean of 2200, mean annual precipitation (mm) on a scale of 500 to 1000 with a mean of 750, temperature (C) on a scale of 4 to 15 with a mean of 7 and log watershed area (km2) on a scale of 0 to 3 with a mean of 1.25
Environmental gradients of reference sites used to develop the Arizona perennial warm water MMI and used for NAMC’s model applicability test

  • Method for accounting for natural environmental gradients: Elevation category and reference site selection criteria
  • Predictors of reference assemblages or metrics: none
  • Metrics used
    • total richness
    • # Diptera taxa
    • # intolerant taxa
    • # scraper taxa
    • % scraper
    • % Plecoptera
    • Hilsenhoff Biotic Index
  • Fixed count: 500
  • Minimum count: unspecified
  • Operational Taxonomic Unit (OTU) applied: No
  • Rare taxa <0.5 probability of capture included: Yes
  • Documentation