Mississippi River IA 01-NEM-77
from Wisconsin R. near McGregor (Clayton Co.) to Lock & Dam 9 near Harpers Ferry Allamakee Co.
- 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 3:24:55 PM
- Updated
- 11/17/2016 2:49:07 PM
The Class A1 (primary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment. The Class B(WW1) aquatic life uses remain assessed (monitored) as "fully supporting" based on results of ambient chemical/physical water quality monitoring. Fish consumption uses are assessed (monitored) as “fully supported" based on results of fish contaminant monitoring in 2011, 2013 and 2014. The sources of data used for this assessment include (1) the results of routine chemical/physical water quality monitoring conducted at station M646.9X at Gordon’s Bay Landing from January 2002 through June 2006 by staff of the Upper Mississippi River Long-Term Resource Monitoring Program (LTRMP) at the Fayette field office, (2) results of monitoring by U.S. EPA Region 7 from April 2010 to November 2012, and (3) Iowa DNR fish contaminant monitoring near Harpers Ferry in 2011 and near Marquette/McGregor in 2013 and 2014.
The Class A1 uses remain “not assessed” due to lack of information on levels of indicator bacteria in this reach of river. The Class B(WW1) (aquatic life) uses remain assessed (evaluated) as “fully supported” based on results of water quality monitoring from LTRMP station M646.9X at Gordon’s Bay Landing. Results of monitoring from 2002-06 at this station show no violations of Class B(WW1) water quality criteria for dissolved oxygen or for ammonia-nitrogen in the 51 samples collected. Two of the 73 samples (3%) collected violated the Class B(WW1) criterion for pH. The pH in the samples collected on April 23 and May 7, 2004 were both 9.3; these values exceed Iowa’s Class B(WW1) criterion of 9.0 pH units. According to U.S. EPA guidelines (U.S. EPA 1997b, page 3-17), however, a violation frequency of less than 10 % for conventional parameters such as pH does not suggest impairment of aquatic life uses. Thus, the results of water quality monitoring at this station suggest “full support” of the Class B(WW1) aquatic life uses. Notes: monitoring at station M646.9X ended in June 2006. Monitoring by U.S. EPA Region 7 from April 2010 to November 2012 shows no violations of Class B(WW1) criteria for dissolved oxygen or pH in the nine samples analyzed. Fish consumption uses are assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring at Harpers Slough near Harpers Ferry in 2011 and near Marquette/McGregor in 2013 and 2014. In the 2011 sampling, the composite samples of fillets from common carp had low levels of contaminants: mercury: 0.064 ppm; total PCBs: <0.09 ppm; and technical chlordane: <0.03 ppm. The average levels of mercury in the tissue plug samples from black crappie was 0.012 ppm. In the 2013 sampling near McGregor, the average level of mercury in the tissue plugs from five largemouth bass was 0.263 ppm. Because this level approached the one meal/week consumption advisory threshold of 0.3 ppm, Iowa DNR follow-up monitoring was conducted in 2014 to better define the level of mercury in predator fish. Results of the 2014 sampling showed a very low average level of mercury (0.05 ppm) in the tissue plugs from five Largemouth Bass. This level is far below the 0.3 ppm advisory threshold for mercury. 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 levels of contaminants in the samples of common carp and black crappie from RAFT monitoring in 2011 do not exceed any of Iowa’s advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this river segment.