Assessment Summary
The Class A1 use was assessed (monitored) as "not supported" due to frequent violations of the state criterion for pH and due to aesthetically objectionable conditions caused by non-algal turbidity. The Class BLW use was assessed (monitored) as "not supported" due to frequent violations of the state criterion for pH and "WINOFI" due to the occurrence of a fish kill. All other designated uses were "not assessed."
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 remains placed in IR Category 4a (impaired; TMDL approved).
Assessment Explanation
Data Sources:
|
Data Source
|
Data Source ID
|
Data Type
|
Data Age
|
Site ID
|
Site
Name
|
Site
Description
|
|
Iowa DNR
|
6
|
WQ
|
CY 2016-2019
|
22780001
|
Carter
Lake Max Depth
|
|
Class A1 - Indicator Bacteria: No Data
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
|
|
22780001
|
6
|
12 / 4
|
7.4
|
8.4
|
8
|
0
|
4
|
NO
|
Monitored
|
Full
|
According to DNR's methodology, a lake must meet water
quality standards for two consecutive cycles to suggest
de-listing. Therefore, Carter Lake will remain listed for the 2022
cycle as "not supported" its Class A1 use 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
|
|
22780001
|
6
|
Chlorophyll a TSI
|
12 / 4
|
36
|
80
|
56
|
NO
|
Monitored
|
Full
|
|
22780001
|
6
|
Secchi TSI
|
12 / 4
|
48
|
81
|
74
|
YES
|
Monitored
|
Not
|
|
22780001
|
6
|
Total Phosphorus TSI
|
12 / 4
|
56
|
73
|
66
|
NA
|
NA
|
NA
|
|
22780001
|
6
|
Inorganic suspended solids
|
12 / 4
|
0.6
|
21
|
8.8
|
NA
|
NA
|
NA
|
Class BLW - 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
|
|
22780001
|
6
|
Ammonia
|
12 / 4
|
0.0003
|
0.03
|
0.01
|
NA
|
0 / 0
|
4
|
NO
|
Monitored
|
Full
|
|
22780001
|
6
|
Dissolved Oxygen
|
12 / 4
|
1.8
|
9.2
|
6.1
|
3
|
NA / NA
|
4
|
NO
|
Monitored
|
Full
|
|
22780001
|
6
|
pH
|
12 / 4
|
7.4
|
8.4
|
8
|
0
|
NA / NA
|
4
|
NO
|
Monitored
|
Full
|
|
22780001
|
6
|
Temperature
|
12 / 4
|
20.6
|
29.6
|
25.4
|
0
|
NA / NA
|
4
|
NO
|
Monitored
|
Full
|
According to DNR's methodology, a lakemust meet water
quality standards for two consecutive cycles to suggest
de-listing. Therefore, Carter Lake will remain listed for the 2022
cycle as "not supported" its Class BLW use 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 Concentration = 75th Percentile
|
Assessment Type
|
Support Level
|
|
22780001
|
6
|
6
|
48.81
|
94.2%
|
8.37
|
64.1%
|
NO
|
Evaluated
|
NA
|
Class BLW - Fish Kill:
The Class BLW use was historically assessed as “WINOFI” due to a 2010 fish kill. Because no
additional fish kills were reported in the segment for a 10 year period (2010-2020), the
assessment category for the fish kill was changed from 3b to 3a (not assessed).
Class HH - No Data
The Class HH use of this lake was historically impaired based on a consumption advisory issued by the state of Nebraska due to high levels of PCBs. The PCB consumption advisory was removed; therefore, the Class HH use of this lake was "not assessed."
