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

Pilot Branch Stennett

Analysis Summary for Series #1545

Benthic Macroinvertebrate Index of Biotic Integrity (BMIBI)

Metric Name Value Score
MH Total Taxa 33 10
SH Total Taxa 9 7.9
MH EPT Taxa 7 4.97
SH EPT Taxa 4.33 5.71
MH Sensitive Taxa 0 0
SH Ephem % 10.38 1.33
SH EPT % 77.31 8.1
SH Chiron % 15.42 8.55
SH Scraper % 5.09 1.14
SH Top3Dom % 73.78 8.6
SH Dom FFG % 66.58 5.57
MHBI 5.78 4.52
*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 9/16/2013
Sampling Series Series #1545
Drainage Area (mi2) 6.51
Log(DA) 0.813580988568192
Calculation Last Updated 7/22/2025 3:36:35 PM
Sampling Gear Hess
BMIBI Score
55
Warm Water
Fair

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and habitat specialists are rare; EPT taxa are still dominant in abundance; however, the most-sensitive EPT taxa have been replaced by ept taxa that are more tolerant of organic enrichment; the community is not well-balanced; a few taxa clearly dominate in abundance, collector-gatherers or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 Reference Site. Reference sites represent natural stream qualities that are least disturbed by human activities within the watershed. These sites are then grouped by ecoregion to establish a benchmark against which other streams in the same ecoregion 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 55
Total Reference Site Samples 37
Mean 53.73
Standard Deviation 10.44