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 2018-2020
|
10360003
|
Nishnabotna River near Hamburg
|
|
|
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
|
111
|
Nishnabotna
River
|
at
Hamburg
|
Class A1 - Indicator Bacteria:
|
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 A – 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
|
0
|
7
|
NO
|
Monitored
|
Full
|
Class BWW1 -
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
|
|
10360003
|
6
|
Ammonia
|
36 / 3
|
0.025
|
0.4
|
0.05
|
NA
|
0 / 0
|
7
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Chloride
|
36 / 3
|
9
|
18
|
13
|
NA
|
0 / 0
|
7
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Dissolved Oxygen
|
36 / 3
|
7
|
13.5
|
10.2
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
pH
|
36 / 3
|
7.2
|
8.7
|
8
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Sulfate
|
36 / 3
|
13
|
32
|
21
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Temperature
|
36 / 3
|
0
|
28.8
|
12.9
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
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
|
Aluminum
|
14 / 3
|
23
|
5.44
|
2.7
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Arsenic
|
13 / 3
|
3.6
|
2.3
|
2.3
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Cadmium
|
13 / 3
|
0.025
|
0.025
|
0.025
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Chromium
|
13 / 3
|
1.1
|
0.6
|
0.7
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Lead
|
13 / 3
|
0.23
|
0.1
|
0.08
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Nickel
|
13 / 3
|
3.7
|
2.8
|
2.8
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Silver
|
13 / 3
|
0.025
|
0.025
|
0.025
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10360003
|
6
|
Zinc
|
13 / 3
|
4.1
|
2
|
2.2
|
0 / 0
|
NO
|
Monitored
|
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
|
|
388
|
10/6/20
|
2818
|
47m
|
MO
|
Floating Art Sub
|
29
|
Poor
|
54
|
Fail
|
|
928
|
8/13/18
|
2807
|
47m
|
MO
|
Floating Art Sub
|
45
|
Fair
|
54
|
Fail
|
|
928
|
9/6/16
|
2807
|
47m
|
MO
|
Floating Art Sub
|
46
|
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
|
2818
|
47m
|
MO
|
NA
|
30
|
Fair
|
31
|
Pass
|
Overall:
|
Community
|
Assessment Type
|
Assessment Result
|
Support Level
|
IR Category
|
Reason
|
|
Benthic
Macroinvertebrates
|
Evaluated
|
Fail (0/3)
|
Not
|
|
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 (2016/2017/2018/ 2019/2020)
|
DO Criteria Type
|
# 2016 violations /
Violations needed for impairment
|
# 2017 violations /
Violations needed for impairment
|
# 2018 violations
/ Violations needed for impairment
|
# 2019 violations /
Violations needed for impairment
|
# 2020 violations /
Violations needed for impairment
|
Violates Annual Significantly >10% Rule?
|
Assessment Type
|
Support Level
|
|
|
|
|
24 hr
|
NA
|
NA
|
NA
|
NA
|
0/4
|
No
|
|
|
|
388
|
6
|
0/0/0/0/14
|
16 hr
|
NA
|
NA
|
NA
|
NA
|
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)
|
|
111
|
whole
|
2016
|
common carp
|
5
|
53
|
0.05
|
0.06
|
0.06
|
|
Support Level
|
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 Human Health designated use will be considered
(evaluated) as “WINOFI.”
