Indian Creek IA 03-SSK-943

mouth (S32 T80N R20W Jasper Co.) to confluence of East Indian and West Indian creeks in S16 T82N R22W Story Co.

This is a DRAFT assessment

Draft assessments may change without notice

Open Data Collection Period Modal

For purposes of developing stream/river water quality assessments for integrated reporting, three years of water quality data are typically used for both conventional pollutant parameters (e.g., indicator bacteria) and the less frequently monitored toxic parameters (e.g., toxic metals). Since the 2004 IR cycle, DNR has used a three-year data gathering period for streams, rivers, and beaches. For most assessments, the use of three years of data increases the number of samples upon which the decision on use support is based and helps address the problem of weather-related year-to-year fluctuations in water quality.

Due to the lower sampling frequency in Iowa’s ambient lake, biological, fish kill, and fish tissue monitoring programs, five years of data are used for developing IR assessments and for identifying Section 303(d) listings.

Data Type	Data Timeframe
Beach Sampling Data	CY 2022 - 2024
Stream/River Water Quality Data	CY 2022 - 2024
Lake Water Quality Data	CY 2020 - 2024
Biological Sampling Data	CY 2020 - 2024*
Fish Kill Data	CY 2020 - 2024
Fish Tissue Sampling Data	CY 2020 - 2024
Continuous Dissolved Oxygen Sampling Data	CY 2020 - 2024
*Biological sites sampled in both 2019 and 2023 were also assessed.

Open Segment Map
View 2026 assessment summary page

Cycle: 2026
Current Phase: Public Comment
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Improving
Trend Comment: Recent benthic macroinvertebrate sampling results allowed for the removal of an aquatic life impairment.
Created: 10/27/2025 3:09:44 PM
Updated: 1/14/2026 9:32:22 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

Impairment Delistings

Cycle Added	Class	Cause	Data Source	Rationale
2016	Class BWW2	Biological: low aquatic macroinvertebrate IBI	Biological monitoring: Iowa DNR WQMA	New data: recovery of fish/invertebrate community

Documentation

Assessment Summary

The presumptive Class A1 use remains assessed as "not supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW2 use was assessed as "fully supported" based on biological sampling data and also on water quality monitoring data.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2022-2024	10500001	Indian Creek near Mingo
PCCB	29	WQ	CY 2022-2024	99990271	Indian Creek
Iowa DNR	6	WQ	CY 2021	376	Indian Creek
Iowa DNR	6	BIO	See Below	376	Indian Creek	Mingo (REMAP #90)
Iowa DNR	6	BIO	See Below	919	Indian Creek	Colfax

Presumptive Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2022/ 2023/2024)

2022 Geometric Mean

2023 Geometric Mean

2024 Geometric Mean

Violates Annual Geometric Mean?

# 2022 SSM violations / SSM Violations needed for impairment

# 2023 SSM violations / SSM Violations needed for impairment

# 2024 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

10500001

8/8/8

309

380

668

YES

3 / 3

4 / 3

7 / 3

YES

MONITORED

NOT

Presumptive 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
10500001	6	36 / 3	7.3	8.4	8.1	0	7	NO	MONITORED	FULL

Class BWW2 - 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
10500001	6	Chloride	36 / 3	24	58	35	NA	0 / 0	7	NO	MONITORED	FULL
10500001	6	Dissolved Oxygen	36 / 3	7.7	15	10.2	0	NA / NA	7	NO	MONITORED	FULL
10500001	6	pH	36 / 3	7.3	8.4	8.1	0	NA / NA	7	NO	MONITORED	FULL
10500001	6	Sulfate	36 / 3	14	62	33	0	NA / NA	7	NO	MONITORED	FULL
10500001	6	Temperature	36 / 3	0	29.8	11.9	0	NA / NA	7	NO	MONITORED	FULL
99990271	29	Temperature	59 / 3	1.1	30.6	13.97	0	NA / NA	10	NO	MONITORED	FULL

Class BWW2 - 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
10500001	6	Ammonia	36 / 3	0.38	0.05	0.02	0 / 0	NO	MONITORED	FULL
10500001	6	Cadmium	18 / 2	0.5	0.5	0.5	0 / 0	NO	MONITORED	FULL
10500001	6	Chromium	18 / 2	28	2.98	0.94	1 / 1	NO	MONITORED	FULL
10500001	6	Copper	18 / 2	3.8	1.3	1.2	0 / 0	NO	MONITORED	FULL
10500001	6	Lead	18 / 2	1	1	1	0 / 0	NO	MONITORED	FULL
10500001	6	Nickel	18 / 2	2.2	1.6	1.6	0 / 0	NO	MONITORED	FULL
10500001	6	Selenium	36 / 3	3	1.2	1	0 / 0	NO	MONITORED	FULL
10500001	6	Silver	18 / 2	1	1	1	0 / 0	NO	MONITORED	FULL
10500001	6	Zinc	18 / 2	1.7	0.6	0.5	0 / 0	NO	MONITORED	FULL

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	BMIBI BIT	BMIBI Pass/Fail
919	8/9/23	395.0	47f	MS	Floating ArtSub	52	Fair	51	Pass
376	9/16/21	254.9	47b	MS	Low Flow ArtSub	34	Fair	62	Fail
919	7/18/19	395.0	47f	MS	Floating ArtSub	65	Good	51	Pass

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47f FIBI BIT	FIBI Pass/Fail
376	9/16/21	254.9	47b	MS	NA	29	Fair	32	Pass*

Overall Assessment:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Monitored	Pass (2/3)	Full		*The FIBI score passed using the 7 pt. UAV applied to single samples.
Fish	Evaluated	Pass (1/1)	Full		Assessment was monitored because the BMIBI samples used to complete
Overall	Monitored	Pass	Full	1	the assessment were collected in a recent five-year period.

Class BWW2- Continuous DO Monitoring:

Site ID	Data Source ID	# Days Monitoring (2021)	DO Criteria Type	# 2021 violations / Violations needed for impairment	Violates Annual Significantly >10% Rule?	Assessment Type	Support Level
			24 hr	0/4	No
376	6	16	16 hr	0/4	No	Evaluated	Full

Monitoring and Methods

Assessment Key Dates

7/18/2019

Biological Monitoring

1/6/2022

Monitoring Start

12/16/2024

Monitoring End

8/9/2023

Biological Monitoring

9/16/2021

Biological Monitoring

9/1/2021

Monitoring Start

9/16/2021

Monitoring End

Methods

200

Physical/Chemical Monitoring

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring

860

Other Agencies/Organizations provided monitoring data