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

East Nishnabotna River Shenandoah

Analysis Summary for Series #2407

Benthic Macroinvertebrate Index of Biotic Integrity (BMIBI)

Metric Name Value Score
MH Total Taxa 25 4.81
SH Total Taxa 5.67 2.5
MH EPT Taxa 11 4.07
SH EPT Taxa 4.33 2.95
MH Sensitive Taxa 3 2.73
SH Ephem % 1.5 0.19
SH EPT % 18.4 1.93
SH Chiron % 81.31 1.89
SH Scraper % 0.3 0.07
SH Top3Dom % 97.33 0.42
SH Dom FFG % 82.2 2.97
MHBI 5.85 4.26
*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 8/12/2020
Sampling Series Series #2407
Drainage Area (mi2) 1021.794
Log(DA) 3.00936334816564
Calculation Last Updated 7/22/2025 3:33:09 PM
Sampling Gear Float ArtSub
BMIBI Score
24
Warm Water
Poor

BMIBI Score Explained

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

Sites that score between 0 - 30 are considered poor. Severely impaired macroinvertebrate community. Low numbers of taxa present, sensitive species not present, EPT taxa are rare or not present; community extremely unbalanced; dominated by a few pollution tolerant organisms; some trophic functional feeding groups are not represented. Total numbers of organisms may be low. Total taxa richness and EPT taxa richness are noticeably reduced from optimum levels; sensitive species and habitat specialists are rare; EPT taxa no longer dominate the macroinvertebrate community. Taxa that are tolerant of organic enrichment and/or excessive sediment loads are dominant; the community is unbalanced; a few generalist taxa make up a high percentage of the organisms present; collector-gatherers or collector-filterers are very 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 62
Median 53
25th Percentile 46
Min 28
This Session's Score 24
Total Reference Site Samples 39
Mean 53.74
Standard Deviation 10.33