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

West Nishnabotna River Malvern

Analysis Summary for Series #1990

Benthic Macroinvertebrate Index of Biotic Integrity (BMIBI)

Metric Name Value Score
MH Total Taxa 14 2.69
SH Total Taxa 10 4.41
MH EPT Taxa 7 2.59
SH EPT Taxa 7 4.76
MH Sensitive Taxa 4 3.64
SH Ephem % 17.31 2.21
SH EPT % 96.15 10
SH Chiron % 1.92 9.91
SH Scraper % 0 0
SH Top3Dom % 81.73 2.9
SH Dom FFG % 75.96 4.01
MHBI 6.07 3.44
*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 9/7/2016
Sampling Series Series #1990
Drainage Area (mi2) 967
Log(DA) 2.985426474083
Calculation Last Updated 10/28/2025 3:00:11 PM
Sampling Gear Float ArtSub
BMIBI Score
42
Warm Water
Fair
Series Analysis Notes

Only two art subs present. Plates appeared to be scoured by high flow.

BMIBI Score Explained

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

Sites that score between 31 - 55 are considered fair. Total taxa richness and EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness are noticeably reduced from optimum levels; sensitive species and habitat specialists are rare; EPT taxa are still dominant in abundance; however, the most-sensitive EPT taxa have been replaced by ept taxa that are more tolerant of organic enrichment; the community is not well-balanced; a few taxa clearly dominate in abundance, collector-gatherers or collector-filterers often comprise more than 50% of the community.

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 42
Total Reference Site Samples 37
Mean 53.73
Standard Deviation 10.44