South Fork Iowa River IA 02-IOW-748

from confluence with unnamed tributary in SE 1/4 NE 1/4 S2 T87N R21W (SE of Logsdon Park) Hardin Co. confluence with unnamed tributary in W 1/2 S19 T88N R21W Hardin Co.

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 2018 - 2020
Stream/River Water Quality Data	CY 2018 - 2020
Lake Water Quality Data	CY 2016 - 2020
Biological Sampling Data	CY 2016 - 2020*
Fish Kill Data	CY 2016 - 2020
Fish Tissue Sampling Data	CY 2016 - 2020
Continuous Dissolved Oxygen Sampling Data	CY 2016 - 2020
*Biological sites sampled in both 2015 and 2019 were also assessed.

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Cycle: 2022
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 12/27/2021 6:52:12 AM
Updated: 1/25/2022 12:58:33 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Fully Supported

Class BWW1

Aquatic Life - Warm Water Type 1

Not Supported

Biological: low aquatic macroinvertebrate IBI

Support Level

Not Supported

Impairment Code

5b-v - Biological - verified

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2016

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

TMDL Priority

Tier IV

Organic Enrichment: Low Dissolved Oxygen

Support Level

Further Investigation Needed

Impairment Code

3b - Use potentially impaired based on an evaluated assessment.

Cause Magnitude

Slight

Status

New

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2022

Impairment Rationale

Significantly > 10% of days fail to meet 24-hour criteria

Data Source

Ambient monitoring: Iowa DNR-continuous

Class HH

Human Health -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as "fully supported" based on water quality monitoring data. The Class BWW1 use was assessed as “not supported” based on biological sampling data and "WINOFI" based on continuous dissolved oxygen monitoring data. All other designated uses were "not assessed."

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2019-2020	12420001	South Fork Iowa River Logsdon Co Park- Iowa Falls
Iowa DNR	6	WQ	CY 2018-2020	14000242	South Fork Iowa River 3
Iowa DNR	6	WQ	CY 2019-2020	14000297	South Fork Iowa River 5
Iowa DNR	6	WQ	CY 2018-2018	16420001	South Fork Iowa River - Buckeye - REMAP # 79
Iowa DNR	6	BIO	See Below	21	South Fork Iowa River	Logsdon County Park – Iowa Falls
Iowa DNR	6	BIO	See Below	380	South Fork Iowa River	Buckeye – REMAP #79
Iowa DNR	6	BIO	See Below	1194	South Fork Iowa River	E of Buckeye – SFI-3
Iowa DNR	6	BIO	See Below	1229	South Fork Iowa River	4 miles E of Buckeye – SFI-5

Presumptive Class A1 - Indicator Bacteria: No Data

Class A - 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
12420001	6	27 / 2	7.7	8.4	8.1	0	6	NO	Monitored	Full
14000242	6	36 / 3	6.8	8.3	8	0	7	NO	Monitored	Full
14000297	6	27 / 2	7.21	8.35	7.98	0	6	NO	Monitored	Full
16420001	6	8 / 1	6.9	8.3	8	0	3	NO	Evaluated	Full

Class BWW1 - 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
12420001	6	Ammonia	26 / 2	0.02	0.15	0.03	NA	0 / 0	6	NO	Monitored	Full
14000242	6	Ammonia	34 / 3	0.025	0.2	0.03	NA	0 / 0	7	NO	Monitored	Full
16420001	6	Ammonia	8 / 1	0.02	0.08	0.03	NA	0 / 0	3	NO	Evaluated	Full
12420001	6	Dissolved Oxygen	27 / 2	4.23	14.06	8.65	1	NA / NA	6	NO	Monitored	Full
14000242	6	Dissolved Oxygen	36 / 3	5.88	14.02	8.82	0	NA / NA	7	NO	Monitored	Full
14000297	6	Dissolved Oxygen	27 / 2	5.63	13.82	9.05	0	NA / NA	6	NO	Monitored	Full
16420001	6	Dissolved Oxygen	8 / 1	8	12.2	9.2	0	NA / NA	3	NO	Evaluated	Full
12420001	6	pH	27 / 2	7.7	8.4	8.1	0	NA / NA	6	NO	Monitored	Full
14000242	6	pH	36 / 3	6.8	8.3	8	0	NA / NA	7	NO	Monitored	Full
14000297	6	pH	27 / 2	7.21	8.35	7.98	0	NA / NA	6	NO	Monitored	Full
16420001	6	pH	8 / 1	6.9	8.3	8	0	NA / NA	3	NO	Evaluated	Full
12420001	6	Temperature	27 / 2	3.2	27.3	18.4	0	NA / NA	6	NO	Monitored	Full
14000242	6	Temperature	36 / 3	2.3	26.2	17.3	0	NA / NA	7	NO	Monitored	Full
14000297	6	Temperature	27 / 2	4	25.4	16.7	0	NA / NA	6	NO	Monitored	Full
16420001	6	Temperature	8 / 1	15.99	25.23	21.39	0	NA / NA	3	NO	Evaluated	Full

Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47b BMIBI BIT	BMIBI Pass/Fail
21	10/6/20	47b	MS	120.8	Surber	34	Fair	62	Fail
1194	10/5/20	47b	MS	112.0	Surber	48	Fair	62	Fail
1229	10/5/20	47b	MS	118.0	Surber	43	Fair	62	Fail
21	8/27/20	47b	MS	120.8	Surber	56	Good	62	Fail
1194	8/25/20	47b	MS	112.0	Surber	58	Good	62	Fail
1229	8/24/20	47b	MS	118.0	Surber	54	Fair	62	Fail
1229	7/22/20	47b	MS	118.0	Hess	56	Good	62	Fail
1194	7/21/20	47b	MS	112.0	Surber	57	Good	62	Fail
21	7/20/20	47b	MS	120.8	Hess	64	Good	62	Pass
1229	8/28/19	47b	MS	118.0	Hess	57	Good	62	Fail
1194	8/27/19	47b	MS	112.0	Hess	50	Fair	62	Fail
21	8/14/19	47b	MS	120.8	Surber	62	Good	62	Pass
21	8/9/16	47b	MS	120.8	Hess	59	Good	62	Fail

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47b FIBI BIT	FIBI Pass/Fail
21	8/27/20	120.8	47b	MS	Yes	72	Excellent	53	Pass
1194	8/25/20	112.0	47b	MS	Yes	67	Good	53	Pass
1229	8/25/20	118.0	47b	MS	Yes	55	Good	53	Pass
380	8/24/20	113.0	47b	MS	No	71	Excellent	32	Pass
1229	8/28/19	118.0	47b	MS	Yes	58	Good	53	Pass
1194	8/27/19	112.0	47b	MS	Yes	70	Good	53	Pass
21	8/14/19	120.8	47b	MS	Yes	65	Good	53	Pass
21	8/9/16	120.8	47b	MS	Yes	59	Good	53	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Monitored	Fail (2/13)	Not
Fish	Monitored	Pass (8/8)	Full	5bv	Assessment was monitored because the samples used to complete
Overall	Monitored	Fail	Not		the assessment were collected in a recent five year period.

Class BWW1 - Continuous DO Monitoring:

Site ID	Data Source ID	# Days Monitoring (2016/2017/2018/ 2019/2020)	DO Criteria Type	# 2016 violations / Violations needed for impairment	# 2017 violations / Violations needed for impairment	# 2018 violations / Violations needed for impairment	# 2019 violations / Violations needed for impairment	# 2020 violations / Violations needed for impairment	Violates Annual Significantly >10% Rule?	Assessment Type	Support Level
			24 hr	NA	NA	NA	NA	6/4	Yes
380	6	0/0/0/0/16	16 hr	NA	NA	NA	NA	0/4	No	Evaluated	WINOFI

Class HH – No Data

Monitoring and Methods

Assessment Key Dates

8/14/2019

Biological Monitoring

8/9/2016

Biological Monitoring

5/15/2018

Non-fixed Monitoring Start Date

10/28/2020

Non-fixed Monitoring End Date

8/27/2019

Biological Monitoring

8/28/2019

Biological Monitoring

7/20/2020

Biological Monitoring

7/21/2020

Biological Monitoring

7/22/2020

Biological Monitoring

8/24/2020

Biological Monitoring

8/25/2020

Biological Monitoring

8/27/2020

Biological Monitoring

10/5/2020

Biological Monitoring

10/6/2020

Biological Monitoring

Methods

222

Non-fixed-station monitoring (conventional during key seasons and flows)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

380

Quantitative physical habitat assessment