Iowa DNR
Iowa DNR

ADBNet

Water Quality Assessments
Impaired Waters List

McKinley Lake IA 05-PLA-1470

Union County S11T72NR31W at W edge of Creston.

This is a DRAFT assessment
Draft assessments may change without notice
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trophic
Eutrophic
Trend
Stable
Current Phase
Public Comment
Created
10/27/2025 3:10:16 PM by
Updated
11/21/2025 3:16:54 PM by
Use Support
Class A1
Recreation - Primary contact
Not Supported
Support Level
Not Supported
Impairment Code
5a - Pollutant-caused impairment. TMDL needed.
Cause Magnitude
Slight
303(d) Listing Status
Continuing
Source
Multiple Sources
Source Confidence
Moderate
Cycle Added
2022
Impairment Rationale
Narrative criteria violation: aesthetically objectionable conditions
Data Source
Ambient monitoring: Iowa DNR-lakes
TMDL Priority
Tier I
Support Level
Not Supported
Impairment Code
5a - Pollutant-caused impairment. TMDL needed.
Cause Magnitude
Moderate
303(d) Listing Status
Continuing
Source
Other: Sediment Resuspension
Source Confidence
Moderate
Cycle Added
2022
Impairment Rationale
Narrative criteria violation: aesthetically objectionable conditions
Data Source
Ambient monitoring: Iowa DNR-lakes
TMDL Priority
Tier I
Support Level
Not Supported
Impairment Code
5a - Pollutant-caused impairment. TMDL needed.
Cause Magnitude
Slight
303(d) Listing Status
New
Source
Other: Algae Blooms
Source Confidence
Moderate
Cycle Added
2026
Impairment Rationale
Significantly > 10% of samples fail to meet criterion
Data Source
Ambient monitoring: Iowa DNR-lakes
TMDL Priority
Tier III
Class BLW
Aquatic Life - Lakes and wetlands
Not Supported
Support Level
Not Supported
Impairment Code
5a - Pollutant-caused impairment. TMDL needed.
Cause Magnitude
Slight
303(d) Listing Status
New
Source
Other: Algae Blooms
Source Confidence
Moderate
Cycle Added
2026
Impairment Rationale
Significantly > 10% of samples fail to meet criterion
Data Source
Ambient monitoring: Iowa DNR-lakes
TMDL Priority
Tier III
Class HH
Human Health -
Not Supported
Support Level
Not Supported
Impairment Code
5a - Pollutant-caused impairment. TMDL needed.
Cause Magnitude
Slight
303(d) Listing Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2012
Impairment Rationale
Fish consumption advisory in effect: no more than 1 meal/week
Data Source
Fish contaminant monitoring: Iowa DNR
TMDL Priority
Tier IV
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class A1 use was assessed (monitored) as “not supported” due to aesthetically objectionable conditions caused by poor water transparency, nuisance blooms of algae and violations of the pH Criteria. The Class BLW use was assessed (monitored) as “not supported” due to violations of the pH Criteria. The Class HH (fish consumption) use remains assessed (evaluated) as "not supported" (IR 5a) based on fish tissue sampling data and due to the existence of a one meal/week PCBs consumption advisory for channel catfish on this segment.

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

WQ

CY 2020-2024

14000244

McKinley Lake

Class A - 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

14000244

6

11 / 4

8.1

9.4

8.7

4

3

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

14000244

6

Chlorophyll a TSI

14 / 5

40

90

72

YES

MONITORED

NOT

14000244

6

Secchi TSI

14 / 5

71

93

77

YES

MONITORED

NOT

14000244

6

Total Phosphorus TSI

14 / 5

71

90

76

NA

NA

NA

14000244

6

Fixed suspended solids

14 / 5

2.7

28

17.4

NA

NA

NA

Class BLW - Binomial 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

14000244

6

Dissolved Oxygen

14 / 5

4.9

12.3

8.2

1

NA / NA

4

NO

MONITORED

FULL

14000244

6

pH

11 / 4

8.1

9.4

8.7

4

NA / NA

3

YES

MONITORED

NOT

14000244

6

Temperature

14 / 5

21.7

27

24.9

0

NA / NA

4

NO

MONITORED

FULL

Class BLW - 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

14000244

6

Ammonia

11 / 4

0.316

0.11

0.1

0 / 0

NO

MONITORED

FULL

Class HH - Fish Tissue Sampling:

Site ID

Biopart

Year

Species

# in sample / # of samples

Avg Length (cm)

(Avg) Hg (ppm)

Chlordane (ppm)

Sum PCBs (ppm)

1260

fillet

2023

common carp

3

36.32

0.033

<0.05

0.0891

Support Level

NOT

According to DNR's methodology, a two consecutive fish tissue samples below the criteria that are collected during the monitoring window are required to suggest de-listing. Therefore, McKinley Lake will remain listed for the current assessment cycle as "not supported" for its Class HH uses due to PCBs.


Monitoring and Methods
Assessment Key Dates
6/26/2015
Fish Tissue Monitoring
6/15/2020
Monitoring Start
7/8/2024
Monitoring End
10/24/2023
Fish Tissue Monitoring
Methods
150
Monitoring data more than 5 years old
200
Physical/Chemical Monitoring
260
Fish tissue analysis