California

The California Stream Condition Index (CSCI) is an MMI and O/E index averaged together. It was created to address California state biocriteria in 2015 by an interagency group of researchers including NAMC (Mazor et al. 2016). To calculate the CSCI, macroinvertebrates should be identified to NAMC’s standard taxonomic resolution and collected June -August for the North Coast & Central Valley Sacramento, June-September for Sierras & Modoc, and May-July for Southern California.

Index # Reference Sites # Degraded Sites Index mean Index SD Moderate departure from reference benchmark Major departure from reference benchmark Narrative conditions
CSCI 474 497 1.01 0.12 < 0.92 <= 0.79 Good: likely intact, Fair: possibly intact, Poor: likely or very likely altered

California with CSCI reference sites represented as black dots
California Stream Condition Index (CSCI) macroinvertebrate reference sites

Box plots of catch elevation(m) on a scale of 0 to 3500 with a mean of 1500, mean annual precipitation (mm) on a scale of 0 to 3500 with a mean of 1000, temperature (C) on a scale of 0 to 20 with a mean of 9 and log watershed area (km2) on a scale of 0 to 3.5 with a mean of 1.4
Environmental gradients of reference sites used to develop the CSCI and used for NAMC’s model applicability test

  • Method for accounting for natural environmental gradients: Random forest model predicting group membership and individual metrics
  • Predictors of reference assemblages or metrics: 
    • Area of the watershed in sq km
    • Soil bulk density across the watershed
    • Range between max and min elevations
    • Soil Erodibility across the watershed (K factor)
    • Latitude of the point
    • Longitude of the point
    • Watershed mean whole rock P2O5
    • 10-year (2000-2009) average
    • precipitation at the sample point
    • Elevation of the point
    • Watershed mean of mean June–September 1971–2000 monthly precipitation
    • 10-year (2000-2009) average air temperature at the sample point
  • # of Macroinvertebrate groups obtained by hierarchical cluster analysis: 10
  • Metrics:
    • Taxonomic Richness
    • Shredder Taxa Richness
    • Percent Clinger Taxa
    • Percent Coleoptera Taxa
    • Percent
    • EPT Taxa
    • Percent Intolerant Individuals
  • Fixed count: 300
  • Minimum count: unspecified
  • Operational Taxonomic Unit (OTU) applied: Yes
  • Rare taxa <0.5 probability of capture included: No
  • Documentation: Mazor , R. D., A. C. Rehn, P. R. Ode, M. Engeln, K. C. Schiff, E. D. Stein, D. J. Gillett, D. B. Herbst, and C. P. Hawkins. 2016. Bioassessment in complex environments: Designing an index for consistent meaning in different settings. Freshwater Science 35:249–271.