Assessment Summary
The Class A1 use is assessed (monitored) as "not supported" due to frequent violations of the state criterion for pH. The Class BLW use is assessed (monitored) as "not supported" due to frequent violations of the state criterion for pH and due to the occurrence of a fish kill. Class HH use remains assessed (monitored) as "partially supported" due to the existence of a fish consumption advisory issued by the state of Nebraska.
Note: A TMDL for algae/algal toxins, chlorophyll a, total phosphorus, total nitrogen, and pH at Carter Lake was prepared by DNR and the Nebraska Department of Environmental Management and approved by EPA in 2007. Because all Section 303(d) impairments identified for the current assessment/listing cycle (pH) are addressed by the TMDL, this waterbody is placed in IR Category 4a (impaired; TMDL approved).
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 2014-2018
|
22780001
|
Carter Lake Max Depth
|
|
Class A1 -
Indicator Bacteria: No Data
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
|
|
22780001
|
6
|
15 / 5
|
9.5
|
8.5
|
8.3
|
4
|
27%
|
YES
|
Monitored
|
Not
|
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
|
|
22780001
|
6
|
Chlorophyll a TSI
|
15 / 5
|
36
|
80
|
52
|
NO
|
Monitored
|
Full
|
|
22780001
|
6
|
Secchi TSI
|
15 / 5
|
41
|
77
|
63
|
NO
|
Monitored
|
Full
|
|
22780001
|
6
|
Total Phosphorus TSI
|
15 / 5
|
49
|
71
|
65
|
NA
|
NA
|
NA
|
|
22780001
|
6
|
Inorganic suspended solids
|
15 / 5
|
0.7
|
21
|
5.5
|
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
|
|
22780001
|
6
|
Ammonia
|
15 / 5
|
0.03
|
0.01
|
0.01
|
0 / 0
|
0% / 0%
|
NO
|
Monitored
|
Full
|
|
22780001
|
6
|
Dissolved oxygen
|
15 / 5
|
10.3
|
7
|
7
|
NA / 2
|
NA / 13%
|
NO
|
Monitored
|
Full
|
|
22780001
|
6
|
pH
|
15 / 5
|
9.5
|
8.5
|
8.3
|
4 / NA
|
27% / NA
|
YES
|
Monitored
|
Not
|
|
22780001
|
6
|
Temperature
|
15 / 5
|
29.6
|
24.83
|
24.72
|
0 / 0
|
0% / 0%
|
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 Wet Mass = 75th
Percentile
|
Assessment Type
|
Support Level
|
|
22780001
|
6
|
11
|
48.806
|
95 %
|
5.201
|
64.7 %
|
NO
|
Evaluated
|
NA
|
Class BLW - Fish Kill:
The Class BLW use remains assessed (evaluated) as “partially supported” due to fish kills that occurred in March of 2010. Because the cause of the fish kill was not identified, or the fish kill was attributed to a non-pollutant cause (e.g., winterkill), the assessment type is “evaluated.” Segments assessed using “evaluated” assessments are placed in Category 3b and are added to the state list of waters in need of further investigation. If no additional fish kills are reported in the segment for a 10 year period, the Category will be changed from 3b to 3a (water not assessed).
Details about the 2010 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/815
Class HH - Fish Tissue Sampling: Adjecient State Information
Fish consumption use remains assessed (monitored) as "partially supported" due to the continuation of a fish consumption advisory for this lake issued by the state of Nebraska due to high levels of PCBs (for more information, see the following web site:http://deq.ne.gov/publica.nsf/pages/WAT257. 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. According to DNR’s assessment methodology, the existence of a restricted consumption advisory indicates that fish consumption uses should be assessed as “partially supported.”
