Iowa DNR
Iowa DNR

ADBNet

Water Quality Assessments
Impaired Waters List

Lotts Creek IA 05-GRA-1376

IA/MO line (S24 TT67N R29W Ringgold Co.) to confluence with Tuckers Cr. in S12 T67N R29W Ringgold Co.

This is a DRAFT assessment
Draft assessments may change without notice
Overall IR
4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend
Stable
Current Phase
Public Comment
Created
10/27/2025 3:09:59 PM by
Updated
1/15/2026 12:58:27 PM by
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW2
Aquatic Life - Warm Water Type 2
Not Supported
Support Level
Not Supported
Impairment Code
4c - Non-pollutant caused impairment. No TMDL needed.
Cause Magnitude
Slight
303(d) Listing Status
Delisted
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2006
Impairment Rationale
Low Biotic Index
Cycle Delisted
2026
Delisting Rationale
New data: recovery of fish/invertebrate community
Data Source
Biological monitoring: Iowa DNR WQMA
Cycle Added Class Cause Data Source Rationale
2006 Class BWW2 Biological: low fish IBI Biological monitoring: Iowa DNR WQMA New data: recovery of fish/invertebrate community
Documentation
Assessment Summary

The Class BWW2 use was assessed as "not supported"; however, the Category 5bv impairment was delisted and moved to Category 4c (Non-pollutant caused impairment. No TMDL needed) based on biological and physical habitat sampling data. All other designated uses remain "not assessed."

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

BIO

See Below

60

Lotts Creek

Ringgold SWMA – Lamoni


Presumptive Class A1 - No Data


Class BWW2 - Biological Sampling:


Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/Thermal

BM Sample Gear

BMIBI score

BMIBI Class

40a BMIBI BIT

BMIBI Pass/Fail

60

8/2/22

61.1

40a

MO/WW

Surber

57

Good

41

Pass

60

7/17/18

61.1

40a

MO/WW

Surber

63

Good

41

Pass


Fish:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/Thermal

Riffle Stream?

FIBI score

FIBI Class

40a FIBI BIT

FIBI Pass/Fail

60

8/2/22

61.1

40a

MO/WW

NA

35

Fair

33

Pass

60

7/17/18

61.1

40a

MO/WW

NA

31

Fair

33

Fail


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Pass (2/2)

Full

Fish

Evaluated

Fail (1/2)

Not

Overall

Evaluated

Fail

Not

4c

Category 5bv impairment delisted, Category 4c habitat impairment remains.


Class BWW2 – Habitat Index Evaluation:

For Lotts Creek, the observed FIBI scores were higher than the EFHI-predicted FIBI scores. When the observed FIBI score-EFHI-predicted FIBI score difference is

+8 to -5 points, water quality and/or other factors besides physical habitat do not limit the stream’s ability to meet the FIBI BIT. The fact that EFHI scores are below the 40a FIBI BIT

is an indication that Lotts Creek will have difficulty meeting the 40a FIBI BIT because of habitat conditions at the site. In addition, because both the 2018 and 2022 BMIBI scores

overwhelmingly passed the 40a BMIBI BIT is an indication that there is not a water quality problem in this segment.

BioNet Site ID

Sample Date

FIBI Score

40a FIBI BIT

EFHI Score

FIBI-BIT Difference

FIBI-EFHI Difference

EFHI-BIT Difference

60

8/2/22

35

33

27

2

8

-6

60

7/17/18

31

33

28

-2

3

-5



Monitoring and Methods
Assessment Key Dates
7/17/2018
Biological Monitoring
8/2/2022
Biological Monitoring
Methods
150
Monitoring data more than 5 years old
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys
380
Quantitative physical habitat assessment