Assessment Summary
The Class A1 use was assessed as "not supported" due to violations of the state criteria for indicator bacteria. The Class BWW1 use was assessed as “WINOFI” based on biological sampling data. The Class HH (fish consumption) use was assessed as “WINOFI” due to detectable levels of DDE and dieldrin in 2013 and 2014.
Assessment Explanation
Data Sources:
|
Data Source
|
Data Source ID
|
Data Type
|
Data Age
|
Site ID
|
Site
Name
|
Site
Description
|
|
Iowa DNR
|
6
|
WQ
|
CY 2014-2016, CY 2020-2022
|
10360003
|
Nishnabotna
River near Hamburg
|
|
|
USGS
|
11
|
WQ
|
CY 2012-2014
|
6810000
|
Nishnabotna
River above Hamburg, IA
|
|
|
Iowa DNR
|
6
|
BIO
|
See Below
|
388
|
Nishnabotna
River
|
Hamburg
(REMAP #43)
|
|
Iowa DNR
|
6
|
BIO
|
See Below
|
928
|
Nishnabotna
River
|
Hamburg
|
|
Iowa DNR
|
6
|
FT
|
See Below
|
1110
|
Nishnabotna
River
|
at Hamburg
|
Class A1 - Indicator Bacteria: 2014-2016
|
Site ID
|
Data Source ID
|
# Samples / # Years
|
2014 Geo. Mean
|
2015 Geo. Mean
|
2016 Geo. Mean
|
Annual Geometric Mean Violation
|
# Violations
|
% Violations
|
Significantly >10% Violations
|
Assessment Type
|
Support Level
|
|
10360003
|
6
|
23 / 3
|
900
|
296
|
1734
|
Yes
|
12
|
52%
|
Yes
|
Evaluated
|
Not
|
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
|
|
10360003
|
6
|
36 / 3
|
7.2
|
8.7
|
8.1
|
0
|
7
|
NO
|
Mon
|
Full
|
Class BWW1 - Binomial 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
|
|
10360003
|
6
|
Chloride
|
36 / 3
|
12
|
20
|
16
|
NA
|
0 / 0
|
7
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Dissolved Oxygen
|
36 / 3
|
5.3
|
13.4
|
10.2
|
0
|
NA / NA
|
7
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
pH
|
36 / 3
|
7.2
|
8.7
|
8.1
|
0
|
NA / NA
|
7
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Sulfate
|
36 / 3
|
16
|
33
|
25
|
0
|
NA / NA
|
7
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Temperature
|
36 / 3
|
0
|
28.9
|
13.9
|
0
|
NA / NA
|
7
|
NO
|
Mon
|
Full
|
Class BWW1 - 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
|
|
10360003
|
6
|
Ammonia
|
36 / 3
|
0.43
|
0.04
|
0.02
|
0 / 0
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Cadmium
|
19 / 3
|
0.5
|
0.4
|
0.5
|
0 / 0
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Chromium
|
19 / 3
|
6
|
0.83
|
0.5
|
0 / 0
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Lead
|
19 / 3
|
3.6
|
1
|
1
|
0 / 0
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Nickel
|
19 / 3
|
4.6
|
1.9
|
1.6
|
0 / 0
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Selenium
|
18 / 2
|
5
|
2
|
2
|
0 / 0
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Silver
|
19 / 3
|
1
|
0.897
|
1
|
0 / 0
|
NO
|
Mon
|
Full
|
|
10360003
|
6
|
Zinc
|
19 / 3
|
9.2
|
1.2
|
0.5
|
0 / 0
|
NO
|
Mon
|
Full
|
Class BWW1 - Biological Sampling:
Benthic Macroinvertebrates:
|
Site ID
|
Date
|
Drainage Area (mi2)
|
Ecoregion
|
Major Drainage
|
BM Sample Gear
|
BMIBI score
|
BMIBI Class
|
47m BMIBI BIT
|
BMIBI Pass/Fail
|
|
928
|
9/13/22
|
2807.0
|
47m
|
MO
|
Floating Art Sub
|
28
|
Poor
|
54
|
Fail
|
|
388
|
10/6/20
|
2817.8
|
47m
|
MO
|
Floating Art Sub
|
29
|
Poor
|
54
|
Fail
|
|
928
|
8/13/18
|
2807.0
|
47m
|
MO
|
Floating Art Sub
|
45
|
Fair
|
54
|
Fail
|
Fish:
|
Site ID
|
Date
|
Drainage Area (mi2)
|
Ecoregion
|
Major Drainage
|
Riffle Stream?
|
FIBI score
|
FIBI Class
|
47m FIBI BIT
|
FIBI Pass/Fail
|
|
388
|
10/6/20
|
2817.8
|
47m
|
MO
|
NA
|
30
|
Fair
|
31
|
Pass
|
Overall:
|
Community
|
Assessment Type
|
Assessment Result
|
Support Level
|
IR Category
|
Reason
|
|
Benthic
Macroinvertebrates
|
Evaluated
|
Fail (0/3)
|
WINOFI
|
|
The FIBI score passed using the 7 point UAV
applied to single samples.
|
|
Fish
|
Evaluated
|
Pass (1/1)
|
Full
|
|
Assessment was evaluated because the
drainage areas of the sample sites
|
|
Overall
|
Evaluated
|
Fail
|
WINOFI
|
3bu
|
were larger than the calibrated range.
|
Class BWW1- Continuous DO Monitoring:
|
Site ID
|
Data Source ID
|
# Days Monitoring (2020)
|
DO Criteria Type
|
# 2020 violations / Violations needed for impairment
|
Violates Annual Significantly >10% Rule?
|
Assessment Type
|
Support Level
|
|
|
|
24 hr
|
0/4
|
No
|
|
|
|
388
|
6
|
14
|
16 hr
|
0/4
|
No
|
Evaluated
|
Full
|
Class HH - Fish Tissue Sampling:
|
Site ID
|
Biopart
|
Year
|
Species
|
# in sample / # of samples
|
Avg Length (cm)
|
(Avg) Hg (ppm)
|
Chlordane (ppm)
|
Sum PCBs (ppm)
|
|
1110
|
whole
|
2016
|
common carp
|
5
|
53
|
0.05
|
0.06
|
0.06
|
|
Support Level
|
Full
|
|
|
|
|
|
|
|
Class HH-F - Toxic Parameters:
|
Site ID
|
Data Source ID
|
Parameter Name
|
# Samples / # Years
|
Maximum Value
|
Mean Value
|
Median Value
|
Number of Non - Detects
|
Mean Value > Criterion or MCL
|
Assessment Type
|
Support Level
|
|
10360003
|
6
|
Selenium
|
18 / 2
|
5
|
2
|
2
|
0
|
NO
|
Mon
|
Full
|
Class HH – Historic Assessment:
The results of USGS
monitoring from 2012 and 2014 showed one of the 33 samples (3%) analyzed for
DDE and three of the 33 samples (9%) analyzed for Dieldrin exceeded criteria.
The sample collected on January 16, 2013 at USGS station 6810000 (near Hamburg)
had a detectable level of DDE of 0.003 ug/l, thus exceeding the HH-fish
criterion of 0.0022 ug/l. Levels of DDE the remainder of the samples at this
monitoring stations were reported as less than the levels of detection (0.002
ug/l and 0.005 ug/l). The samples collected on June 10, 2014, July 15, 2014 and
September 16, 2014 at USGS station 06810000 (near Hamburg) had detectable
levels of dieldrin of 0.004 ug/l, 0.003 ug/l and 0.003 ug/l respectively, thus
exceeding the HH-fish criterion of 0.00054 ug/l. Levels of dieldrin the
remainder of the samples at this monitoring stations were reported as less than
the level of detection (0.008 ug/l). According to DNR’s assessment/listing
methodology, if the average level of a toxic metal or pesticide is greater than
its respective human health criterion, impairment ("WINOFI") of the
Human Health use is indicated. The number of samples with detectable levels of
DDE and dieldrin at these monitoring stations (1/33 and 3/33), however, is too few
and the method detection level is far too high (~16 times greater than the HH
criterion for dieldrin) to allow calculation of a meaningful summary statistic
(e.g., mean) for DDE and dieldrin at this monitoring station. Based on sampling
that shows detectable levels of DDE and dieldrin, however, the Class HH use was
considered (evaluated) as “WINOFI.”
