Assessment Summary
The Class A1 use was assessed as "not supported" based on levels of indicator bacteria that exceeded state water quality criteria. The Class BWW1 use remains assessed as “not supported” based on fish kills in and upstream from this segment. All other designated uses were "not assessed."
Assessment Explanation
Data Sources:
|
Data Source
|
Data Source ID
|
Data Type
|
Data Age
|
Site ID
|
Site Name
|
Site Description
|
|
Iowa DNR
|
6
|
WQ
|
CY 2018-2020
|
10890001
|
Des Moines River near Keosauqua
|
|
|
USGS
|
11
|
WQ
|
CY 2018-2020
|
5490500
|
Des Moines River at Keosauqua, IA
|
|
|
Iowa
DNR
|
6
|
BIO
|
See
Below
|
946
|
Des Moines River
|
Keosauqua
|
|
Iowa
DNR
|
6
|
BIO
|
See
Below
|
1258
|
Des Moines River
|
Bonaparte – REMAP #414
|
Class A1 -
Indicator Bacteria:
|
Site ID
|
Data Source ID
|
# Samples per Year (2018/ 2019/2020)
|
2018 Geometric Mean
|
2019 Geometric Mean
|
2020 Geometric Mean
|
Violates Annual Geometric Mean?
|
# 2018 SSM violations / SSM Violations
needed for impairment
|
# 2019 SSM violations / SSM Violations
needed for impairment
|
# 2020 SSM violations / SSM Violations
needed for impairment
|
Violates Annual SSM Significantly >10%
Rule?
|
Assessment Type
|
Support Level
|
|
10890001
|
6
|
8/8/8
|
49
|
158
|
106
|
YES
|
1 / 3
|
2 / 3
|
1 / 3
|
NO
|
Monitored
|
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
|
|
10890001
|
6
|
36 / 3
|
7.7
|
8.8
|
8.3
|
0
|
7
|
NO
|
Monitored
|
Full
|
|
5490500
|
11
|
40 / 3
|
7.4
|
9
|
8.2
|
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
|
|
10890001
|
6
|
Ammonia
|
36 / 3
|
0.02
|
0.54
|
0.06
|
NA
|
0 / 0
|
7
|
NO
|
Monitored
|
Full
|
|
5490500
|
11
|
Ammonia
|
38 / 3
|
0.005
|
0.46
|
0.07
|
NA
|
0 / 0
|
7
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Chloride
|
36 / 3
|
11
|
54
|
25
|
NA
|
0 / 0
|
7
|
NO
|
Monitored
|
Full
|
|
5490500
|
11
|
Chloride
|
41 / 3
|
10.1
|
58.3
|
23.7
|
NA
|
0 / 0
|
8
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Dissolved Oxygen
|
36 / 3
|
7
|
19.8
|
11
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
Full
|
|
5490500
|
11
|
Dissolved Oxygen
|
40 / 3
|
6.4
|
15
|
10.7
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
pH
|
36 / 3
|
7.7
|
8.8
|
8.3
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
Full
|
|
5490500
|
11
|
pH
|
40 / 3
|
7.4
|
9
|
8.2
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Sulfate
|
36 / 3
|
18
|
110
|
50
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
Full
|
|
5490500
|
11
|
Sulfate
|
41 / 3
|
17
|
118
|
48
|
0
|
NA / NA
|
8
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Temperature
|
36 / 3
|
0.1
|
29.3
|
12.6
|
0
|
NA / NA
|
7
|
NO
|
Monitored
|
Full
|
|
5490500
|
11
|
Temperature
|
39 / 3
|
-0.1
|
29.2
|
15.6
|
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
|
|
10890001
|
6
|
Aluminum
|
14 / 3
|
10
|
1.188
|
0.39
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Arsenic
|
13 / 3
|
4.3
|
2.3
|
2.1
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
5490500
|
11
|
Arsenic
|
41 / 3
|
6
|
2.5
|
2.2
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Cadmium
|
13 / 3
|
0.07
|
0.03
|
0.02
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Chromium
|
13 / 3
|
1.2
|
0.8
|
0.8
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Lead
|
13 / 3
|
0.39
|
0.17
|
0.13
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Nickel
|
13 / 3
|
4.4
|
3.5
|
3.6
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Silver
|
13 / 3
|
0.025
|
0.025
|
0.025
|
0 / 0
|
NO
|
Monitored
|
Full
|
|
10890001
|
6
|
Zinc
|
13 / 3
|
4
|
2.16
|
2.1
|
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
|
40a BMIBI BIT
|
BMIBI Pass/ Fail
|
|
946
|
7/27/20
|
14038
|
40a
|
MS
|
Floating Art Sub
|
60
|
Good
|
41
|
Pass
|
|
1258
|
7/27/20
|
14100
|
40a
|
MS
|
Hess
|
58
|
Good
|
41
|
Pass
|
|
946
|
9/6/16
|
14038
|
40a
|
MS
|
Floating Art Sub
|
74
|
Good
|
41
|
Pass
|
Fish:
|
Site ID
|
Date
|
Drainage Area (mi2)
|
Ecoregion
|
Major Drainage
|
Riffle Stream?
|
FIBI score
|
FIBI Class
|
40a FIBI BIT
|
FIBI Pass/ Fail
|
|
1258
|
7/28/20
|
14100
|
40a
|
MS
|
NA
|
30
|
Fair
|
33
|
Pass
|
Overall:
|
Community
|
Assessment Type
|
Assessment Result
|
Support Level
|
IR Category
|
Reason
|
|
Benthic
Macroinvertebrates
|
Evaluated
|
Pass (3/3)
|
Full
|
|
Assessment was evaluated
because the drainage areas of the sites
|
|
Fish
|
Evaluated
|
Pass (1/1)
|
Full
|
1
|
were greater than the
calibrated range.
|
|
Overall
|
Evaluated
|
Pass
|
Full
|
|
The FIBI score passed
after using the 7 point UAV applied to single samples.
|
Class BWW1 – Fishkill Assessment:
The Class BWW1 aquatic life use remains assessed as “not supported” due to fish kills on July 10, 2006, and on July 7, 2012 on the reach of river between Eldon (Wapello Co.) and Douds (Van Buren Co.). These kills are in a series of kills that have occurred over the last 20 years that appear to involve primarily shovelnose sturgeon (Scaphirhynchus platorynchus). Although the cause fish kills remains unknown, the leading hypotheses are (1) that very high water temperatures, very low river flows, and elevated pH levels combine to make ambient levels of ammonia in the river toxic to the ammonia-intolerant shovelnose sturgeon and (2) that the kills are caused by a virus specific to shovelnose sturgeon. The most recent kill in July 2012 was especially severe. According to the local DNR Fisheries biologist, the kill was reported on the lower Des Moines River on July 7, 2012, from approximately Eldon (downriver from Ottumwa) to Farmington in Van Buren County. An estimated 57,000 fish were killed including at least 35,000 shovelnose sturgeon. No specific cause of the kill was identified, but low flow conditions, flow alterations, and very high water temperatures (95+F) are believed to have contributed to the kill.
According to DNR’s assessment methodology, if a cause of a fish kill was not identified during the DNR investigation (cause = "unknown"), or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated.” Such assessments typically lack the degree of confidence to support addition to the state Section 303(d) list of impaired waters (Category 5 of the Integrated Report). Waterbodies affected by such fish kills are usually placed in IR subcategory 3b and are added to the state’s list of waters in need of further investigation (WINOFI). Due however to (1) the repeated occurrence of these kills over the last 20 years in Wapello and Van Buren counties, (2) the large numbers of sturgeon killed (thousands), (3) the likelihood that these kills are caused by a pollutant and (4) the possibility that the kills have extended further downstream (possibly to Bonaparte), this impairment remains on Iowa’s Section 303(d) list (Category 5 of the Integrated Report).
Class HH - No Data
