Old Mans Creek IA 02-IOW-686
from confluence with unnamed tributary (N line S1 T78N R7W Johnson Co.) to confluence with unnamed tributary in NE 1/4 S4 T78N R8W Johnson Co.
The presumptive Class A1 use remains assessed as "not supported" due to levels of indicator bacteria that violated state water quality criteria. The Class BWW2 use was assessed as "fully supported” based on biological sampling data and water quality monitoring data. Note: A TMDL covering the bacteria impairments for all segments, with the segment code prefix "IA 02-IOW" in the Iowa River Basin, was approved by EPA in 2018. Due to the completion of the TMDL, the IR category for the Class A1 use was changed from 5p (impaired; TMDL needed) to 4a (impaired; TMDL approved).
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2022-2024 10520001 Old
Mans Creek near Iowa City
Iowa DNR 6 BIO See Below 1047 Old
Mans Creek Sharon
Center Iowa DNR 6 BIO See Below 5 Old
Mans Creek Williamstown Presumptive Class A1 - Indicator Bacteria: Site ID Data Source ID # Samples per Year (2022/ 2023/2024) 2022 Geometric Mean 2023 Geometric Mean 2024 Geometric Mean Violates Annual Geometric Mean? # 2022 SSM violations / SSM Violations needed for impairment # 2023 SSM violations / SSM Violations needed for impairment # 2024 SSM violations / SSM Violations needed for impairment Violates Annual SSM Significantly >10% Rule? Assessment Type Support Level 10520001 6 8/8/8 764 330 2551 YES 6 / 3 6 / 3 8 / 3 YES MONITORED NOT Presumptive Class A1 – pH: Site ID Data Source ID # Samples / # Years Minimum Value Maximum Value Mean Value # Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 10520001 6 35 / 3 7.2 8.5 8 0 7 NO MONITORED FULL Class BWW2 - Conventional Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Mean Value # Violations # Acute / Chronic Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 10520001 6 Chloride 36 / 3 24 61 36 NA 0 / 0 7 NO MONITORED FULL 10520001 6 Dissolved Oxygen 36 / 3 7.6 16.3 11.3 0 NA / NA 7 NO MONITORED FULL 10520001 6 pH 35 / 3 7.2 8.5 8 0 NA / NA 7 NO MONITORED FULL 10520001 6 Sulfate 36 / 3 16 110 38 0 NA / NA 7 NO MONITORED FULL 10520001 6 Temperature 36 / 3 0 30 13 0 NA / NA 7 NO MONITORED FULL Class BWW2 - Toxic Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value # Acute / Chronic Violations >1 Acute / Chronic Violation Assessment Type Support Level 10520001 6 Ammonia 35 / 3 0.43 0.06 0.02 0 / 0 NO MONITORED FULL 10520001 6 Cadmium 18 / 2 0.5 0.5 0.5 0 / 0 NO MONITORED FULL 10520001 6 Chromium 18 / 2 2 0.81 0.54 0 / 0 NO MONITORED FULL 10520001 6 Copper 18 / 2 23 2.7 1.2 0 / 1 NO MONITORED FULL 10520001 6 Lead 18 / 2 1 1 1 0 / 0 NO MONITORED FULL 10520001 6 Nickel 18 / 2 3.3 1.9 1.9 0 / 0 NO MONITORED FULL 10520001 6 Selenium 36 / 3 2 0.9 0.5 0 / 0 NO MONITORED FULL 10520001 6 Silver 18 / 2 1 1 1 0 / 0 NO MONITORED FULL 10520001 6 Zinc 18 / 2 6.1 1.3 0.5 0 / 0 NO MONITORED FULL Class BWW2 -
Biological Sampling: Benthic
Macroinvertebrates: Site
ID Date Drainage
Area (mi2) Ecoregion Major
Drainage BM
Sample Gear BMIBI
score BMIBI
Class 47f
BMIBI BIT BMIBI
Pass/Fail 1047 8/12/24 210 47f MS Art
Sub 61 Good 51 Pass 5 9/7/23 138 47f MS Art
Sub 37 Fair 51 Fail 1047 8/7/20 210 47f MS Floating
Art Sub 63 Good 51 Pass Site
ID Date Drainage
Area (mi2) Ecoregion Major
Drainage Riffle
Stream? FIBI
score FIBI
Class 47f
FIBI BIT FIBI
Pass/Fail 5 9/6/23 138 47f MS NA 53 Good 36 Pass 5 9/18/19 138 47f MS NA 53 Good 36 Pass Community Assessment
Type Assessment
Result Support
Level IR
Category Reason Benthic Macroinvertebrates Monitored Pass
(2/3) Full Fish Monitored Pass
(2/2) Full 1 Assessment was monitored because the samples used to
complete Overall Monitored Pass Full the assessment were collected in the recent five year
period.
Fish:
Overall: