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

Ocheyedan River Spencer - US2

Analysis Summary for Series #1347

Benthic Macroinvertebrate Index of Biotic Integrity (BMIBI)

Metric Name Value Score
MH Total Taxa 40 7.69
SH Total Taxa 11.33 4.99
MH EPT Taxa 24 8.89
SH EPT Taxa 9.67 6.58
MH Sensitive Taxa 9 8.18
SH Ephem % 35.66 4.56
SH EPT % 63.19 6.62
SH Chiron % 35.85 6.48
SH Scraper % 5.09 1.14
SH Top3Dom % 66.49 5.32
SH Dom FFG % 65.78 5.7
MHBI 5.21 6.63
*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 8/14/2012
Sampling Series Series #1347
Drainage Area (mi2) 426
Log(DA) 2.62940959910272
Calculation Last Updated 7/22/2025 3:35:07 PM
Sampling Gear ArtSub
BMIBI Score
61
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:

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 61
Total Reference Site Samples 45
Mean 50.91
Standard Deviation 13.26