West Nishnabotna River IA 05-NSH-1444

from confluence with East Branch West Nishnabotna R. (S29 T77N R39W Pottawattamie Co.) to confluence with West Fork West Nishnabotna R. in NW 1/4 S18 T79N R39W Shelby 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 2014 - 2016
Stream/River Water Quality Data	CY 2014 - 2016
Lake Water Quality Data	CY 2012 - 2016
Biological Sampling Data	CY 2012 - 2016*
Fish Kill Data	CY 2012 - 2016
Fish Tissue Sampling Data	CY 2012 - 2016
Continuous Dissolved Oxygen Sampling Data	CY 2012 - 2016
*Biological sites sampled in both 2011 and 2015 were also assessed.

Open Segment Map
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Cycle: 2018
Release Status: Final
Overall IR: 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend: Unknown
Created: 7/30/2019 1:02:56 PM
Updated: 7/30/2019 1:04:13 PM

Use Support

Class A1

Recreation - Primary contact

Not Assessed

Class BWW1

Aquatic Life - Warm Water Type 1

Not Assessed

Class HH

Human Health -

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 (primary contact recreation) uses and the Class B(WW1) aquatic life uses both remain "not assessed" due to the lack of information upon which to base an assessment. The fish consumption uses remain assessed as "fully supported" based on results of U.S. EPA/DNR fish tissue monitoring near Harlan in August 2011.

Assessment Explanation

Fish consumption uses remain assessed (evaluated) as “fully supported” based on results of U.S.EPA/DNR fish contaminant monitoring near Harlan in 2011. The composite samples of fillets from channel catfish had low levels of contaminants. The composite samples of fillets from channel catfish had very low levels of contaminants. Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.028 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of the degree to which Iowa’s lakes and rivers support their fish consumption uses. The fish contaminant data generated from the 2011 RAFT sampling conducted in this segment of the West Nishnabotna River indicate that the levels of contaminants do not exceed any of Iowa’s advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody.

Monitoring and Methods

Assessment Key Dates

8/17/2011

Fish Tissue Monitoring

Methods

150

Monitoring data more than 5 years old

260

Fish tissue analysis