Mississippi River IA 01-NEM-71

from Catfish Cr. at south edge of Dubuque (Dubuque Co.) to Lock & Dam 11 at north edge of Dubuque (Dubuque 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 2012 - 2014
Stream/River Water Quality Data	CY 2012 - 2014
Lake Water Quality Data	CY 2010 - 2014
Biological Sampling Data	CY 2010 - 2014*
Fish Kill Data	CY 2010 - 2014
Fish Tissue Sampling Data	CY 2010 - 2014
Continuous Dissolved Oxygen Sampling Data	CY 2010 - 2014
*Biological sites sampled in both 2009 and 2013 were also assessed.

Open Segment Map
View assessment methodology in new window

Cycle: 2016
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: 3/8/2016 10:01:30 AM
Updated: 11/17/2016 2:45:42 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 are considered “not assessed” due to the lack of monitoring information upon which to base an assessment. Fish consumption uses are assessed (monitored) as "fully supported" based on the removal of the "one meal per week" fish consumption advisory for Pool 12 of the Mississippi River in 2011. The sources of data used for this assessment is the results of Iowa DNR fish contaminant trend monitoring in 2010, 2012 and 2014.

Assessment Explanation

The Class A1 (primary contact recreation) uses remain “not assessed” due to the lack of information upon which to base an assessment. Water quality monitoring conducted by LTRMP does not include analysis for indicator bacteria.

The assessment of the Class B(WW1) (aquatic life) uses is changed from “fully supported” to “not assessed” due to the age of the data upon which previous assessments were based. The most recent water quality monitoring at LTRMP station M582.5B in the tailwater area of Lock and Dam 11 was conducted in 2004. These data are now considered too old (older than 10 year) to characterize current water quality conditions.

Fish consumption uses are assessed (monitored) as "fully supported" based on the removal of the "one meal per week" fish consumption advisory for this Pool 12 of the Mississippi River in 2011 and based on results of fish contaminant monitoring in 2012 (see the 2012 assessment for this segment for details of issuance and removal of the fish consumption advisory for this assessment segment). In addition, this segment has been sampled for whole-fish common carp since 1994 on an every-other-year basis as part of Iowa DNR trend monitoring. The results from the 2010, 2012 and 2014 trend sampling all show low levels of the primary contaminants (chlordane, PCBs and mercury). The results for the 2010 sample are as follows: mercury: 0.111 ppm; total PCBs: 0.277 ppm; and technical chlordane: 0.031 ppm. The results for the 2012 sample are as follows: mercury: 0.069 ppm; total PCBs: 0.142 ppm; and technical chlordane: <0.03 ppm. The results for the 2014 sample are as follows: mercury: 0.05 ppm; total PCBs: 0.24 ppm; and technical chlordane: 0.08 ppm. Although the level of total PCBs in the whole-fish sample from 2014 is slightly above the one-meal/week advisory threshold of 0.2 ppm, the IDPH/IDNR advisory thresholds are not applicable to whole-fish concentrations but rather are appropriate for concentrations of toxic contaminant in the edible portion of fish (fillets). Thus, these results do not suggest the need to issue a consumption advisory for this waterbody for PCBs, and the fish consumption uses for this river segment are assessed (monitored) as “fully supported”.

Monitoring and Methods

Assessment Key Dates

8/4/2010

Fish Tissue Monitoring

9/11/2012

Fish Tissue Monitoring

8/18/2014

Fish Tissue Monitoring

Methods

260

Fish tissue analysis