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

Rock Creek Rock Creek

Analysis Summary for Series #2796

Benthic Macroinvertebrate Index of Biotic Integrity (BMIBI)

Metric Name Value Score
MH Total Taxa 32 6.67
SH Total Taxa 15 7.87
MH EPT Taxa 15 6.67
SH EPT Taxa 9.5 7.32
MH Sensitive Taxa 6 5.92
SH Ephem % 5.45 0.7
SH EPT % 75.05 7.86
SH Chiron % 12.64 8.83
SH Scraper % 10.33 2.31
SH Top3Dom % 70.64 5.15
SH Dom FFG % 68.09 5.32
MHBI 5.19 6.7
*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 7/17/2024
Sampling Series Series #2796
Drainage Area (mi2) 45.65
Log(DA) 1.65944078187032
Calculation Last Updated 7/22/2025 3:34:03 PM
Sampling Gear Hess
BMIBI Score
59
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 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:

Iowan Surface

This site is in the Iowan Surface ecoregion.

Ecoregion Map
Max 91
75th Percentile 75
Median 66
25th Percentile 57
Min 23
This Session's Score 59
Total Reference Site Samples 162
Mean 65.27
Standard Deviation 12.31