Mississippi River IA 01-NEM-76
from Lock & Dam 10 at Guttenberg (Clayton Co.) to confluence with Wisconsin R across from McGregor Clayton 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 11:05:37 AM
- Updated
- 11/17/2016 2:48:21 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 are considered “not assessed” due to the lack of recent water quality information upon which to base an assessment. Fish consumption uses remain assessed (monitored) as "fully supported" based on fish contaminant monitoring in 2007. The source of data used for this assessment is the results of U.S. EPA/DNR fish tissue (RAFT) monitoring in 2007 downstream from Guttenberg.
An assessment of support of the Class A1 (primary contact recreation) uses was not developed due to lack of sufficient data on levels of indicator bacteria in this river reach. LTRMP monitoring 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 M615.2B in the tailwater area of Lock and Dam 10 was conducted from 2002 to 2004. These data are now considered too old (older than 10 year) to characterize current water quality conditions. Fish consumption uses remain assessed (monitored) as “fully supported” based on results of Iowa DNR fish contaminant monitoring downstream of Guttenberg in 2007. 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 composite samples of fillets from the 2007 RAFT sampling had low levels of contaminants. Levels of primary contaminants in the composite sample of common carp fillets in 2007 were as follows: mercury: 0.126 ppm; total PCBs: 0.112 ppm; and technical chlordane: <0.03 ppm. The level of mercury in the composite sample of white bass fillets was 0.065 ppm. The levels of contaminants from the 2007 RAFT sampling do not exceed any of the advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody.