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

Drainage Ditch 81 Nevada (Mixed HWCRS)

Analysis Summary for Series #946

Benthic Macroinvertebrate Index of Biotic Integrity (BMIBI)

Metric Name Value Score
MH Total Taxa 23 6.71
SH Total Taxa 8 6
MH EPT Taxa 3 1.85
SH EPT Taxa 1.67 1.87
MH Sensitive Taxa 2 2.78
SH Ephem % 8.31 1.06
SH EPT % 8.66 0.91
SH Chiron % 41.13 5.95
SH Scraper % 4.32 0.97
SH Top3Dom % 85.35 3.94
SH Dom FFG % 91.15 1.47
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 8/29/2007
Sampling Series Series #946
Drainage Area (mi2) 10.66
Log(DA) 1.02775720469055
Calculation Last Updated 7/22/2025 3:37:28 PM
Sampling Gear Surb
BMIBI Score
31
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and habitat specialists are rare; EPT taxa are still dominant in abundance; however, the most-sensitive EPT taxa have been replaced by ept taxa that are more tolerant of organic enrichment; the community is not well-balanced; a few taxa clearly dominate in abundance, collector-gatherers or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 Candidate Reference Site. Further study is required to determine if this site represents natural stream qualities that are least disturbed by human activities within the watershed.

EcoRegion Comparison

Scores for a sampling session are compared against reference sites within the same ecoregion:

Des Moines Lobe

This site is in the Des Moines Lobe ecoregion.

Ecoregion Map
Max 84
75th Percentile 68
Median 59
25th Percentile 51
Min 10
This Session's Score 31
Total Reference Site Samples 162
Mean 58.11
Standard Deviation 13.08