North Skunk River IA 03-NSK-863

from confluence with Sugar Cr. (S20 T78N R16W Poweshiek Co.) to confluence with Snipe Cr. in S22 T81N R19W Jasper 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 2016 - 2018
Stream/River Water Quality Data	CY 2016 - 2018
Lake Water Quality Data	CY 2014 - 2018
Biological Sampling Data	CY 2014 - 2018*
Fish Kill Data	CY 2014 - 2018
Fish Tissue Sampling Data	CY 2014 - 2018
Continuous Dissolved Oxygen Sampling Data	CY 2014 - 2018
*Biological sites sampled in both 2013 and 2017 were also assessed.

Open Segment Map
View assessment methodology in new window

Cycle: 2020
Release Status: Final
Overall IR: 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend: Unknown
Created: 6/4/2020 9:14:30 AM
Updated: 10/16/2020 10:19:49 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW2

Aquatic Life - Warm Water Type 2

Not Supported

Biological: low fish IBI

Support Level

Not Supported

Impairment Code

4c - Non-pollutant caused impairment. No TMDL needed.

Cause Magnitude

Moderate

Status

Continuing

Source

Hydromodification

Source Confidence

N/A

Cycle Added

2004

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class BWW2 use remains assessed as "not supported" based on biological sampling data. All other designated uses were "not assessed".

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	BIO	See Below	234	North Skunk River	Kellogg City Park – Site #3
Iowa DNR	6	BIO	See Below	235	North Skunk River	Newton – Site #4
Iowa DNR	6	BIO	See Below	236	North Skunk River	Sully – Site #2
Iowa DNR	6	BIO	See Below	1057	North Skunk River	SE of Kellogg – NS002

Presumptive Class A1 - No Data

Class BWW2 - Biological Sampling:

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	Riffle Stream?	FIBI score	FIBI Class	47f FIBI BIT	FIBI Pass/ Fail
1057	8/1/02	170	47f	MS/WW	NA	24	Poor	36	Fail
235	8/9/01	115	47f	MS/WW	NA	16	Poor	36	Fail
234	8/8/01	168	47f	MS/WW	NA	19	Poor	36	Fail
236	8/7/01	243	47f	MS/WW	NA	17	Poor	36	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Fish	Evaluated	Fail (0/4)	Not	4c	4c	Assessment is evaluated because it included samples not collected in the last five years.
This impairment was attributed to a non-pollutant stressor (other habitat alterations) and thus appropriate for Category 4c of Iowa's 2006 Integrated Report. This impairment remains in IR Category 4c.

Monitoring and Methods

Assessment Key Dates

8/7/2001

Biological Monitoring

8/8/2001

Biological Monitoring

8/9/2001

Biological Monitoring

8/1/2002

Biological Monitoring

Methods

150

Monitoring data more than 5 years old

315

Regional reference site approach

330

Fish surveys