Little Sioux River IA 06-LSR-1578

from confluence with Milford Cr. (NW 1/4 S14 T98N R37W Dickinson Co.) to confluence with West Fork Little Sioux R. in S36 T100N R38W Dickinson Co.

Assessment Cycle

2022

Release Status

Final

Data Collection Period

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.

Overall IR Category: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Stable

Created: 12/28/2021 6:28:21 AM
Updated: 1/27/2022 9:50:44 AM

Assessment conducted in accordance with Iowa's 2022 IR methodology

Use Support

Class A1

Recreation

Primary contact

Not Supported

Impairments

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW1

Aquatic Life

Warm Water Type 1

Not Supported

Impairments

Support Level

Not Supported

Impairment Code

5b-t - Biological - tentative

Cause Magnitude

Slight

Status

New

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2022

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

TMDL Priority

Tier IV

Class HH

Human Health

Not Assessed

Impairment Delistings

Cycle Added	Class	Cause	Data Source	Rationale
2016	Class BWW1	Biological: low fish & invert IBIs- cause unknown	Biological monitoring: Iowa DNR WQMA	New data: recovery of fish/invertebrate community

Documentation

Assessment Summary

The Class A1 use was assessed as "not supported" due to levels of indicator bacteria that violated state water quality criteria. The Class BWW1 was assessed as "not supported” based on biological sampling 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 2018-2020	10300001	Little Sioux River near Milford
Iowa DNR	6	BIO	See Below	63	Little Sioux River	Horseshoe Bend County Park - Milford
Iowa DNR	6	BIO	See Below	1148	Little Sioux River	Gravel Road Bridge W of Milford

Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2018/ 2019/2020)

2018 Geometric Mean

2019 Geometric Mean

2020 Geometric Mean

Violates Annual Geometric Mean?

# 2018 SSM violations / SSM Violations needed for impairment

# 2019 SSM violations / SSM Violations needed for impairment

# 2020 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

10300001

1/1/8

3100

440

219

YES

1 / NA

4 / 3

YES

Monitored

Not

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
10300001	6	36 / 3	6.8	8.8	7.9	0	7	NO	Monitored	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
10300001	6	Ammonia	36 / 3	0.025	1.1	0.1	NA	0 / 0	7	NO	Monitored	Full
10300001	6	Chloride	36 / 3	11	28	17	NA	0 / 0	7	NO	Monitored	Full
10300001	6	Dissolved Oxygen	36 / 3	6.1	15.3	10	0	NA / NA	7	NO	Monitored	Full
10300001	6	pH	36 / 3	6.8	8.8	7.9	0	NA / NA	7	NO	Monitored	Full
10300001	6	Sulfate	36 / 3	26	110	66	0	NA / NA	7	NO	Monitored	Full
10300001	6	Temperature	36 / 3	0	26.5	10.6	0	NA / NA	7	NO	Monitored	Full

Class BWW1 - 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
10300001	6	Aluminum	14 / 3	3.2	0.9	0.5	0 / 0	NO	Monitored	Full
10300001	6	Arsenic	13 / 3	4.4	2.3	2	0 / 0	NO	Monitored	Full
10300001	6	Cadmium	13 / 3	0.07	0.03	0.02	0 / 0	NO	Monitored	Full
10300001	6	Chromium	13 / 3	1.7	0.7	0.7	0 / 0	NO	Monitored	Full
10300001	6	Lead	13 / 3	0.29	0.12	0.09	0 / 0	NO	Monitored	Full
10300001	6	Nickel	13 / 3	4.9	3.5	3.2	0 / 0	NO	Monitored	Full
10300001	6	Silver	13 / 3	0.025	0.025	0.025	0 / 0	NO	Monitored	Full
10300001	6	Zinc	13 / 3	3.4	2.1	2	0 / 0	NO	Monitored	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
63	8/4/20	333.4	47b	MO	Art Sub	65	Good	62	Pass
1148	8/5/17	484	47b	MO	Floating Art Sub	73	Good	62	Pass

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47b FIBI BIT	FIBI Pass/Fail
63	8/4/20	333.4	47b	MO	Yes	51	Good	53	Fail
63	8/12/14	333.4	47b	MO	Yes	41	Fair	53	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Monitored	Pass (2/2)	Full
Fish	Evaluated	Fail (0/2)	Not		Assessment was evaluated because samples greater than five years old
Overall	Evaluated	Fail	Not	5bt	were used to complete the (FIBI) assessment.

Class HH – No Data

Monitoring and Methods

Assessment Key Dates

8/12/2014

Biological Monitoring

8/4/2020

Biological Monitoring

8/15/2017

Biological Monitoring

1/5/2016

Fixed Monitoring Start Date

12/6/2018

Fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

230

Fixed station physical/chemical (conventional plus toxic pollutants)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

380

Quantitative physical habitat assessment

420

Indicator bacteria monitoring