Assessment Summary
The Class A1 use of Saylorville Reservoir was assessed (monitored) as "not supported” due to poor water transparency caused by non-algal turbidity. The Class BWW1 use was assessed (monitored) as "fully supported." Class HH use remains assessed (monitored) as "fully supported" based on ACOE-sponsored annual fish contaminant monitoring from 2012-14.
Assessment Explanation
Data Sources:
|
Data Source
|
Data Source ID
|
Data Type
|
Data Age
|
Site ID
|
Site
Name
|
Site
Description
|
|
USACE
|
12
|
WQ
|
CY 2016-2020
|
27770001
|
Saylorville
Reservoir
|
|
|
USACE
|
12
|
WQ
|
CY 2018-2020
|
99990030
|
Oak
Grove Beach (Saylorville Reservoir)
|
|
|
USACE
|
12
|
WQ
|
CY 2018-2019
|
99990031
|
Sandpiper
Beach (Saylorville Reservoir)
|
|
|
USACE
|
|
FT
|
See Below
|
|
Saylorville
Reservoir
|
|
|
Iowa DNR
|
6
|
WQ
|
CY 2016-2016
|
22770005
|
Saylorville
Reservoir
|
|
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
|
|
27770001
|
12
|
9/10/8
|
6
|
2
|
1
|
NO
|
0 / 3
|
0 / 3
|
0 / 3
|
NO
|
Monitored
|
Full
|
|
99990030
|
12
|
1/9/15
|
NA
|
17
|
9
|
NO
|
1 / NA
|
0 / 3
|
1 / 4
|
NO
|
Monitored
|
Full
|
|
99990031
|
12
|
10/12/0
|
27
|
16
|
NA
|
NO
|
2 / 3
|
0 / 4
|
NA
|
NO
|
Monitored
|
Full
|
The 2020 bacteria impairment was listed as “Aesthetics:
Aesthetically Objectionable Conditions” instead of “Bacteria: Indicator Bacteria- E. coli.” The Class A1 “Aesthetics:
Aesthetically Objectionable Conditions” is suggested for delisting under the
reason of assessment error for the 2022 assessment cycle. Additionally, the high 2018 Geometric mean for “Bacteria: Indicator Bacteria-
E. coli” was due to only having one sample. So the listing during the 2020 cycle shouldn't have occurred based on the assessment methodology.Indicator Bacteria- E. coli is assessed as fully supported.
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
|
|
22770005
|
6
|
3 / 1
|
7.9
|
8.1
|
8
|
0
|
2
|
NO
|
Evaluated
|
Full
|
|
27770001
|
12
|
74 / 5
|
6.79
|
9.05
|
8.18
|
1
|
12
|
NO
|
Monitored
|
Full
|
Class A1 - Lake TSI's
|
Site ID
|
Data Source ID
|
Parameter Name
|
# Samples / # Years
|
Minimum Value
|
Maximum Value
|
Median Value
|
Median TSI Violation?
|
Assessment Type
|
Support Level
|
|
22770005
|
6
|
Chlorophyll a TSI
|
3 / 1
|
61
|
67
|
63
|
NO
|
Evaluated
|
Full
|
|
27770001
|
12
|
Chlorophyll a TSI
|
47 / 5
|
31
|
77
|
66
|
YES
|
Monitored
|
Not
|
|
22770005
|
6
|
Secchi TSI
|
3 / 1
|
67
|
67
|
67
|
YES
|
Evaluated
|
Not
|
|
27770001
|
12
|
Secchi TSI
|
74 / 5
|
44
|
79
|
67
|
YES
|
Monitored
|
Not
|
|
22770005
|
6
|
Total Phosphorus TSI
|
3 / 1
|
66
|
76
|
72
|
NA
|
NA
|
NA
|
|
27770001
|
12
|
Total Phosphorus TSI
|
74 / 5
|
47
|
93
|
74
|
NA
|
NA
|
NA
|
|
22770005
|
6
|
Inorganic suspended solids
|
3 / 1
|
8.6
|
11
|
9.3
|
NA
|
NA
|
NA
|
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
|
|
22770005
|
6
|
Ammonia
|
3 / 1
|
0.006
|
0.187
|
0.08
|
NA
|
0 / 0
|
2
|
NO
|
Evaluated
|
Full
|
|
27770001
|
12
|
Ammonia
|
74 / 5
|
0.02
|
0.77
|
0.12
|
NA
|
0 / 0
|
12
|
NO
|
Monitored
|
Full
|
|
22770005
|
6
|
Dissolved Oxygen
|
3 / 1
|
5.6
|
16.2
|
9.4
|
0
|
NA / NA
|
2
|
NO
|
Evaluated
|
Full
|
|
27770001
|
12
|
Dissolved Oxygen
|
74 / 5
|
5.34
|
19.11
|
10.04
|
0
|
NA / NA
|
12
|
NO
|
Monitored
|
Full
|
|
22770005
|
6
|
pH
|
3 / 1
|
7.9
|
8.1
|
8
|
0
|
NA / NA
|
2
|
NO
|
Evaluated
|
Full
|
|
27770001
|
12
|
pH
|
74 / 5
|
6.79
|
9.05
|
8.18
|
1
|
NA / NA
|
12
|
NO
|
Monitored
|
Full
|
|
22770005
|
6
|
Temperature
|
3 / 1
|
17.1
|
25.3
|
22.6
|
0
|
NA / NA
|
2
|
NO
|
Evaluated
|
Full
|
|
27770001
|
12
|
Temperature
|
74 / 5
|
3.8
|
29.4
|
19.5
|
0
|
NA / NA
|
12
|
NO
|
Monitored
|
Full
|
|
99990030
|
12
|
Temperature
|
25 / 2
|
20.7
|
30.4
|
25.9
|
0
|
NA / NA
|
5
|
NO
|
Monitored
|
Full
|
|
99990031
|
12
|
Temperature
|
13 / 1
|
16.1
|
28.2
|
24.6
|
0
|
NA / NA
|
4
|
NO
|
Monitored
|
Full
|
Class BLW - Lake Planktonic Cyanobacteria:
|
Site ID
|
Data Source ID
|
# Samples
|
Maximum Cyanobacteria Wet Mass
|
Maximum Cyanobacteria % Composition
|
Median Cyanobacteria Wet Mass
|
Median Cyanobacteria % Composition
|
Median Cyanobacteria Concentration = 75th Percentile
|
Assessment Type
|
Support Level
|
|
22770005
|
6
|
3
|
2.84
|
33.4%
|
1.95
|
24.0%
|
NO
|
Evaluated
|
NA
|
Class
HH - Fish Tissue Sampling:
Fish consumption uses were
assessed (monitored) as “fully supported” based on results of ACOE/ISU fish
contaminant monitoring at Saylorville Reservoir in 2012-2014. The composite
samples of whole-fish common carp had low levels of contaminants. Levels of
total chlordane in the composite samples were as follows: 2012: 0.002ppm; 2013:
0.004ppm; 2014: 0.130ppm. None of these levels approach the advisory trigger
level of 0.6ppm for chlordane. In 2012, 2013, and 2014, composite samples of
whole-fish carp were analyzed for total PCBs and Aroclors 1248, 1254, and 1260.
Total PCBs in composite samples of whole-fish carp were 0.002 ppm (2012) and
0.002 (2013).PCB Aroclors 1248, 1254, and 1260 were all 0.0002 ppm(2014).The
levels of PCBs seen in fish tissue samples from ISU/ACOE in Saylorville
Reservoir are well below the one meal per week advisory trigger of 0.20 ppm for
total PCBs. The existence of, or potential for, a fish consumption advisory is
the basis for Section 305(b) assessments of the degree to which Iowa’s lakes
and rivers support their fish consumption uses. The levels of contaminants do
not exceed any of the advisory trigger levels, thus indicating no justification
for issuance of a consumption advisory for this waterbody.
