Colorado

To meet state biocriteria, Colorado uses three separate MMIs depending on biotype: mountains (3), plains (2), and transition zone (1). The CO MMIs were revised in 2017 and this is the version NAMC currently applies using an access database (extra cost). To apply the CO MMIs, midges must be identified to genus (extra cost and time) and samples should be collected between late June to November 30th for biotypes 1 and 2 and May 1st to November 30th for biotype 3.

Index # Reference Sites # Degraded Sites Index Mean Index SD Moderate departure from reference benchmark Major departure from reference benchmark Narrative Condition
Colorado - Biotype 1 41 47 55 4.7 <= 45 < 34 Not Impaired, Inconclusive, Likely Impaired
Colorado - Biotype 2 77 16 39.3 6.3 <= 48 < 40 Not Impaired, Inconclusive, Likely Impaired
Colorado - Biotype 3 26 23 47 7.2 <= 42 < 29 Not Impaired, Inconclusive, Likely Impaired

Colorado with biotype 1 areas shaded in gray, biotype 2 areas shaded in yellow, and biotype 3 areas shaded in blue with CO MMI reference sites represented as black dots
Colorado macroinvertebrate reference sites used for each Biotype specific model

Box plots of catch elevation(m) on a scale of 0 to 4000 with a mean of 2750, mean annual precipitation (mm) on a scale of 200 to 1600 with a mean of 750, temperature (C) on a scale of -1 to 12 with a mean of 3 and log watershed area (km2) on a scale of 0 to 4 with a mean of 1.75
Environmental gradients of reference sites used for all three biotypes and used for NAMC’s model applicability test

Biotype 1

  • Method for accounting for natural environmental gradients: quantile regression predicting individual metrics
  • Predictors of reference assemblages or metrics:
    • Summer temperature
  • Metrics used
    • # EPT taxa adjusted for summer temperature
    • % noninsect individuals
    • % EPT taxa excluding Baetidae
    • % Coleoptera individuals
    • % intolerant taxa adjusted for summer temperature
    • % increaser indicator individuals in Biotype 1
    • # clinger taxa adjusted for summer temperature
    • # facultative predator or shredder taxa
  • Fixed count: 300
  • Minimum count: 200
  • Operational Taxonomic Unit (OTU) applied: No
  • Rare taxa <0.5 probability of capture included: Yes
  • Documentation

Biotype 2

  • Method for accounting for natural environmental gradients: quantile regression predicting individual metrics
  • Predictors of reference assemblages or metrics:
    • Day of year
  • Metrics used
    • # EPT taxa adjusted for day of year
    • % EPT taxa excluding Baetidae
    • # clinger taxa
    • # intolerant taxa
    • % decreaser indicator taxa for Biotype 2
    • # facultative predator taxa
    • # facultative scraper taxa
  • Fixed count: 300
  • Minimum count: 200
  • Operational Taxonomic Unit (OTU) applied: No
  • Rare taxa <0.5 probability of capture included: Yes
  • Documentation

Biotype 3

  • Method for accounting for natural environmental gradients: quantile regression predicting individual metrics
  • Predictors of reference assemblages or metrics:
    • Day of year
  • Metrics used
    • total richness
    • % non-insect taxa
    • % EPT taxa excluding Baetidae
    • # sprawler taxa adjusted for day of year
    • # intolerant taxa
    • % increaser indicator individuals in Biotype 3
    • # facultative predator taxa
    • # facultative scraper taxa
  • Fixed count: 300
  • Minimum count: 200
  • Operational Taxonomic Unit (OTU) applied: No
  • Rare taxa <0.5 probability of capture included: Yes
  • Documentation