Iowa DNR
BioNet
River & Stream Biological Monitoring
Fish and Benthic Macroinvertebrate Surveys
Physical Habitat Assessments

West Nishnabotna River Malvern

Analysis Summary for Series #1834

Benthic Macroinvertebrate Index of Biotic Integrity (BMIBI)

Metric Name Value Score
MH Total Taxa 27 5.19
SH Total Taxa 11.67 5.14
MH EPT Taxa 12 4.44
SH EPT Taxa 9.67 6.58
MH Sensitive Taxa 6 5.45
SH Ephem % 36.08 4.61
SH EPT % 91.41 9.57
SH Chiron % 7.59 9.34
SH Scraper % 4.27 0.96
SH Top3Dom % 68.22 5.04
SH Dom FFG % 58.62 6.9
MHBI 5.51 5.52
*Mouse-over metric for full name
**Final IBI is sum of scores multiplied by 0.8333

Analysis Factors

Factor Value
BMIBI Type Warm Water
Sample Date 8/17/2015
Sampling Series Series #1834
Drainage Area (mi2) 967
Log(DA) 2.985426474083
Calculation Last Updated 10/28/2025 3:00:10 PM
Sampling Gear ArtSub
BMIBI Score
57
Warm Water
Good

BMIBI Score Explained

This site was analyzed using the BMIBI-Warm Water assessment methodology.

Sites that score between 56 - 75 are considered good. A slight reduction in number (Ephemeroptera, Plecoptera, Trichoptera) of taxa; however, good numbers of taxa are present, including several sensitive species, EPT taxa are fairly diverse and dominate the community. The most sensitive taxa and some habitat specialists may not be present and/or are reduced in abundance. The community is balanced, with no taxon excessively dominating in abundance. One functional feeding group, often collector filterers or collector gatherers, may be somewhat dominant.

This location has been classified as a survey site. Survey sites are compared to reference sites within the same ecoregion. A reference site represents natural stream qualities that are least disturbed by human activities within the watershed. Reference sites are grouped by ecoregion to establish a benchmark against which these survey streams are compared.

EcoRegion Comparison

Scores for a sampling session are compared against reference sites within the same ecoregion:

Steeply Rolling Loess Prairies

This site is in the Steeply Rolling Loess Prairies ecoregion.

Ecoregion Map
Max 72
75th Percentile 61
Median 53
25th Percentile 47
Min 28
This Session's Score 57
Total Reference Site Samples 37
Mean 53.73
Standard Deviation 10.44