Assessment Summary
The Class A1uses are assessed (monitored) as “not supported” due to levels of indicator bacteria that exceed Iowa’s water quality standard, aesthetically objectionable conditions caused by turbidity, aesthetically objectionable conditions caused by algae blooms and due to frequent violations of the state criterion for pH. The Class BLW uses are assessed (monitored) as “not supported" due to violations to the state's criterion for dissolved oxygen and pH. In Addition, the Class BLW uses are assessed (evaluated) as “partially supported” due to cyanobacteria blooms. The Class C uses remain not assessed due to a lack of enough data upon which to base an assessment. Class HH uses are assessed (monitored) as “fully supported” based on fish tissue sampling.
Note: A TMDL for impacts of siltation and nutrients at Lake of Three Fires was prepared by DNR and approved by EPA in 2002. Additionally, a TMDL for indicator bacteria at Lake of Three Fires was prepared by DNR and approved by EPA in 2010. Because not all Section 303(d) impairments identified for the current assessment/listing cycle (dissolved oxygen and pH) are addressed in the two TMDLs, this lake is placed into IR Category 5a (TMDL needed.)
Assessment Explanation
Sources of
Data:
|
Data Source
|
Data Source ID
|
Data Type
|
Data Age
|
Site ID
|
Site Name
|
Site Description
|
|
Iowa DNR
|
6
|
WQ
|
CY 2016-2018
|
21870001
|
Lake of Three Fires Beach (Lake of Three
Fires State Park)
|
|
|
Iowa DNR
|
6
|
WQ
|
CY 2014-2018
|
22870001
|
Lake of Three Fires Max Depth
|
|
|
Iowa DNR
|
|
FT
|
See Below
|
158
|
Lake of Three Fires
|
|
Class A1 -
Indicator Bacteria:
|
Site ID
|
Data Source ID
|
# Samples / # Years
|
2016 Geometric Mean
|
2017 Geometric Mean
|
2018 Geometric Mean
|
Annual Geometric Mean Violation
|
# Violations
|
% Violations
|
Significantly >10% Violations
|
Assessment Type
|
Support Level
|
|
21870001
|
6
|
40 / 3
|
40.87
|
26.42
|
15.63
|
No
|
4
|
10%
|
NO
|
Monitored
|
Full
|
- According to DNR's methodology, a lake must meet water quality standards for two consecutive cycles to suggest de-listing. Therefore, Lake of Three Fires will remain listed for the 2020 cycle as "partially supported" its Class A1 uses due to indicator bacteria.
Class A1 - pH:
|
Site ID
|
Data Source ID
|
# Samples / # Years
|
Maximum Value
|
Mean Value
|
Median Value
|
# Violations
|
% Violations
|
Significantly >10% Violations
|
Assessment Type
|
Support Level
|
|
22870001
|
6
|
15 / 5
|
9.7
|
8.4
|
8.3
|
3
|
20%
|
NO
|
Monitored
|
Full
|
- According to DNR's methodology, a lake must meet water quality standards for two consecutive cycles to suggest de-listing. Therefore, Lake of Three Fires will remain listed for the 2020 cycle as "not supported" its Class A1 uses due to pH.
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
|
|
22870001
|
6
|
Chlorophyll a TSI
|
15 / 5
|
36
|
82
|
65
|
YES
|
Monitored
|
Not
|
|
22870001
|
6
|
Secchi TSI
|
15 / 5
|
53
|
73
|
68
|
YES
|
Monitored
|
Not
|
|
22870001
|
6
|
Total Phosphorus TSI
|
15 / 5
|
54
|
81
|
73
|
NA
|
NA
|
NA
|
|
22870001
|
6
|
Inorganic suspended solids
|
15 / 5
|
0.6
|
8.8
|
3.2
|
NA
|
NA
|
NA
|
Class BLW -
Conventional Parameters:
|
Site ID
|
Data Source ID
|
Parameter Name
|
# Samples / # Years
|
Maximum Value
|
Mean Value
|
Median Value
|
# Acute / Chronic Violations
|
% Acute/ Chronic Violations
|
Significantly >10% Violations
|
Assessment Type
|
Support Level
|
|
22870001
|
6
|
Ammonia
|
15 / 5
|
0.61575
|
0.11
|
0.03
|
0 / 0
|
0% / 0%
|
NO
|
Monitored
|
Full
|
|
22870001
|
6
|
Dissolved oxygen
|
15 / 5
|
19.3
|
7.2
|
6.9
|
NA / 4
|
NA / 27%
|
YES
|
Monitored
|
Not
|
|
22870001
|
6
|
pH
|
15 / 5
|
9.7
|
8.4
|
8.3
|
3 / NA
|
20% / NA
|
NO
|
Monitored
|
Full
|
|
22870001
|
6
|
Temperature
|
15 / 5
|
30.4
|
24.5
|
24.5
|
0 / 0
|
0% / 0%
|
NO
|
Monitored
|
Full
|
- According to DNR's methodology, a lake must meet water quality standards for two consecutive cycles to suggest de-listing. Therefore, Lake of Three Fires will remain listed for the 2020 cycle as "not supported" its Class BLW uses due to pH.
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 Wet Mass = 75th
Percentile
|
Assessment Type
|
Support Level
|
|
22870001
|
6
|
11
|
115.346
|
99.3 %
|
32.318
|
93.1 %
|
YES
|
Evaluated
|
3b
|
Class C -
Conventional Parameters:
|
Site ID
|
Data Source ID
|
Parameter Name
|
# Samples / # Years
|
Maximum Value
|
Mean Value
|
Median Value
|
# Violations
|
% Violations
|
Significantly >10% Violations
|
Assessment Type
|
Support Level
|
|
22870001
|
6
|
Inorganic nitrogen (nitrate and nitrite)
|
15 / 5
|
2
|
0.28
|
0.03
|
0
|
0%
|
NO
|
Monitored
|
Full
|
- The Class C
uses are not assessed due to the lack of data sufficient for developing a valid
assessment of support of the Class C uses.
Class HH - Fish
Tissue Sampling:
|
Site ID
|
Date
|
Species Name
|
Biopart
|
# in sample
|
chlordane result
|
chlordane violation?
|
PCBs result
|
PCBs violation?
|
Hg result
|
Hg violation?
|
Assessment Type
|
Support Level
|
|
158
|
5/19/17
|
largemouth bass
|
plug
|
3
|
|
|
|
|
0.280
|
No
|
Monitored
|
Full
|
|
158
|
6/29/15
|
largemouth bass
|
plug
|
5
|
|
|
|
|
0.238
|
No
|
Monitored
|
Full
|
