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

Little Sioux River Spencer - DS1

Analysis Summary for Series #1734

Benthic Macroinvertebrate Index of Biotic Integrity (BMIBI)

Metric Name Value Score
MH Total Taxa 25 4.81
SH Total Taxa 7.67 3.38
MH EPT Taxa 10 3.7
SH EPT Taxa 5.33 3.63
MH Sensitive Taxa 1 0.91
SH Ephem % 9.34 1.19
SH EPT % 62.06 6.5
SH Chiron % 36.41 6.42
SH Scraper % 2.11 0.47
SH Top3Dom % 79.15 3.31
SH Dom FFG % 53.65 7.72
MHBI 5.99 3.74
*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 9/8/2014
Sampling Series Series #1734
Drainage Area (mi2) 1104
Log(DA) 3.04296907339318
Calculation Last Updated 7/22/2025 3:37:14 PM
Sampling Gear ArtSub
BMIBI Score
38
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and habitat specialists are rare; EPT taxa are still dominant in abundance; however, the most-sensitive EPT taxa have been replaced by ept taxa that are more tolerant of organic enrichment; the community is not well-balanced; a few taxa clearly dominate in abundance, collector-gatherers or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 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:

Northwest Iowa Loess Prairies

This site is in the Northwest Iowa Loess Prairies ecoregion.

Ecoregion Map
Max 88
75th Percentile 58
Median 51
25th Percentile 45
Min 10
This Session's Score 38
Total Reference Site Samples 45
Mean 50.91
Standard Deviation 13.26