Nevada

NAMC developed the NV MMI in 2013 as a part of a master’s student research project assessing index performance in arid regions. The state of NV does not currently have a standard set of biocriteria it uses so this index is applicable to NV but does not meet state standards. To calculate this index, midges must be identified to genus (extra cost and time) and samples should be collected June 15th -September 15th.

Index # Reference Sites # Degraded Sites Index Mean Index SD Moderate departure from reference benchmark Major departure from reference benchmark Narrative conditions
Nevada 165 60 56 6.2 < 47 <= 45 Reference, Undetermined, Impaired

 

Nevada and its surrounding states with MMI reference sites represented as black dots
Nevada macroinvertebrate reference sites

Box plots of catch elevation(m) on a scale of 750 to 3250 with a mean of 2250, mean annual precipitation (mm) on a scale of 0 to 2000 with a mean of 600, temperature (C) on a scale of 0 to 12 with a mean of 5 and log watershed area (km2) on a scale of 0 to 5 with a mean of 1.5
Environmental gradients of reference sites used to develop the Nevada MMI and used for NAMC’s model applicability test

  • Metrics used
    • # insect taxa
    • # non-insect taxa
    • # clinger taxa
    • shannons diversity
    • collector filterer relative abundance
    • % Ephemeroptera
    • % Plecoptera
  • Fixed count: 300
  • Minimum count: unspecified
  • Operational Taxonomic Unit (OTU) applied: Yes
  • Rare taxa <0.5 probability of capture included: Yes
  • Method for accounting for natural environmental gradients: Random forest model predicting individual metrics
  • Predictors of reference assemblages or metrics:
    • Catchment mean of mean 1994-2006 annual precipitation-weighted mean Ca concentration
    • Catchment mean of mean 1994-2006 annual precipitation-weighted mean Mg concentration
    • Catchment mean of mean 1994-2006 annual precipitation-weighted mean SO4 concentration
    • Soil bulk density across the watershed
    • Base Flow Index across the watershed
    • Watershed mean whole rock CaO
    • Square Root of topo value at the point
    • Maximum elevation in the watershed
    • Mean elevation across the watershed
    • Minimum elevation in the watershed
    • Watershed mean of mean 2000–2009 annual max enhanced vegetation index
    • Watershed mean of Min flow/Max flow for period of record
    • Soil Erodibility across the watershed (K factor)
    • Watershed mean log geometric mean hydraulic conductivity
    • Watershed mean of mean 1961-1990 last day of freeze
    • Catchment mean of mean 1961-1990 annual max number of wet-days
    • Watershed mean of mean 1971-2000 annual precipitation
    • Watershed mean whole rock MgO
    • Watershed mean of mean 1971–2000 annual min monthly precipitation
    • Watershed mean of mean 1961-1990 annual min number of wet-days
    • Precip max at the point
    • Precip max at the watershed
    • Average of minimum precip at the watershed
    • Watershed mean soil permeability
    • Watershed mean whole rock Sulfur
    • Slope calculation based on (Max elev - Min elev)/FlowLengthMax
    • Area of the watershed in sq km
    • Watershed mean of mean June–September 1971–2000 monthly precipitation
    • Temperature max at the point
    • Watershed mean of mean 1971–2000 annual maximum monthly temperature
    • Watershed mean of mean 1971–2000 annual maximum monthly temperature
    • Unconfined compressive strength across the watershed
    • Mean of max number of wet days at the watershed
    • Watershed mean of mean 1961-1990 annual number of wet-days