Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Big Sioux River IA 06-BSR-1523

from confluence with Indian Cr. (S9 T93N R48W Plymouth Co.) to confluence with Rock R. in S1 T95N R48W Sioux Co.

Cycle
2022
Release Status
Final
Overall IR
4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend
Stable
Created
12/29/2021 3:11:34 PM
Updated
1/6/2022 8:38:19 AM
Use Support
Class A1
Recreation - Primary contact
Not Supported
Support Level
Not Supported
Impairment Code
4a - Pollutant-caused impairment. TMDL has been completed.
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2000
Impairment Rationale
Geometric mean criterion exceeded
Data Source
Ambient monitoring: adjacent state
Class BWW1
Aquatic Life - Warm Water Type 1
Fully Supported
Class HH
Human Health -
Fully Supported
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class A1 use was assessed as “not supported” due to violations of Iowa’s water quality criteria for indicator bacteria (E. coli). The Class BWW1 use was assessed as "fully supported" based on the results of ambient chemical/physical water quality monitoring. The Class HH (fish consumption) use was assessed as "fully supported" based on fish tissue sampling. Note: A TMDL for pathogen indicators in this segment of the Big Sioux River was prepared by DNR and the South Dakota Dept. of Environment & Natural Resources; this TMDL was approved by EPA in January 2008. Because all Section 303(d) impairments identified for the current assessment/listing cycle were addressed by the TMDL, this waterbody remains in IR Category 4a (impaired; TMDL approved).

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

SDAK

16

WQ

CY 2018-2020

460667

Big Sioux River

Iowa DNR

6

FT

See Below

65

Big Sioux River

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

460667

16

5/5/5

495

163

35

YES

4 / NA

1 / NA

0 / NA

NA

Evaluated

Not

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

460667

16

36 / 3

7.7

8.7

8.1

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

460667

16

Ammonia

36 / 3

0.02

1.08

0.13

NA

0 / 0

7

NO

Monitored

Full

460667

16

Dissolved Oxygen

36 / 3

7.2

19.9

11.5

0

NA / NA

7

NO

Monitored

Full

460667

16

pH

36 / 3

7.7

8.7

8.1

0

NA / NA

7

NO

Monitored

Full

460667

16

Temperature

36 / 3

1

28

11

0

NA / NA

7

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)

65

fillet

2011

channel catfish

5

42.4

0.056

0.03

0.09

Support Level

Full

Monitoring and Methods
Assessment Key Dates
1/8/2018
Fixed Monitoring Start Date
12/7/2020
Fixed Monitoring End Date
9/15/2011
Fish Tissue Monitoring
1/23/2008
TMDL Completed
Methods
150
Monitoring data more than 5 years old
210
Fixed station physical/chemical monitoring (conventional pollutants only)
260
Fish tissue analysis
420
Indicator bacteria monitoring