Mississippi River IA 01-NEM-75
from Lock & Dam 11 at north side of Dubuque (Dubuque Co.) to Lock & Dam 10 at Guttenberg (Clayton Co.)
- Cycle
- 2018
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 7/30/2019 1:59:02 PM
- Updated
- 7/31/2019 8:04:04 AM
The Class A1 (primary contact recreation) uses remain “not assessed” due to the lack of data upon which to base an assessment. The Class B(WW1) aquatic life uses are assessed (monitored) as "not supporting" (IR Category 5a) based on results of ambient monitoring provided for aluminum by Illinois EPA. Fish consumption uses remain assessed (monitored) as "fully supported." The sources of data used for this assessment are (1) results of monitoring conducted from 2014 to 2016 by the Illinois Environmental Protection Agency at station M-13 at Lock and Dam 11 at Dubuque (river mile 583) and (2) results of Iowa DNR fish tissue monitoring in 2013 near Dubuque (Mud Lake) and in 2007 and 2015 downstream of Guttenberg.
The Class A1 (primary contact recreation) uses remain “not assessed” due to the lack of information upon which to base an assessment. Although ambient monitoring is conducted in this river segment by the Illinois EPA, the resulting data are for fecal coliform bacteria. These data are not applicable to Iowa’s water quality standard for E. coli to protect the designated Class A1 primary contact recreation uses. Water quality monitoring conducted by other agencies in this river segment (e.g., LTRMP) does not include analysis for indicator bacteria. Results of conventional chemical/physical water quality monitoring from Illinois EPA station M-13 suggest “full support” of the aquatic life uses. Monitoring showedno violations of Class B(WW1) water quality criteria for 11 Ammonia samples (maximum = 0.8 mg/L), 10 Dissolved Oxygen samples (minimum = 7.4 mg/L), 12 pH samples (range = 6.7 to 8.8), 12 Temperature samples (maximum = 27°C), 14 Chloride samples (maximum = 24.8 mg/L), or 13 Sulfate samples (maximum = 44.6 mg/L) occurred during monitoring from March 2014 to November 2016.According to U.S. EPA guidelines for Section 305(b) water quality assessments (U.S. EPA 1997b, page 3-17), the EPA guidelines allow up to 10% violations of these conventional parameters before impairment of water quality is indicated. Thus, these results thus suggest “full support” of the Class B(WW1) aquatic life uses.
Fish consumption uses remain assessed (monitored) as “fully supported” based on results of U.S.EPA/DNR fish contaminant (RAFT) monitoring near Dubuque in 2013 and downstream from 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 average level of mercury in tissue plugs from five Largemouth Bass collected in 2013 near Mud Lake was 0.165 ppm; this level is below the one meal/week consumption advisory trigger of 0.3 ppm. For the 2007 sampling downstream from Guttenberg, the levels of primary contaminants were also below the advisory trigger levels. 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.Levels of primary contaminants in the composite sample of common carp fillets in 2015 were as follows: mercury: 0.15 ppm; total PCBs: <0.06 ppm; and technical chlordane: <0.02 ppm.The level of mercury in the composite sample of white bass fillets in 2007 was 0.065 ppm.The level of mercury in the composite sample of largemouth bass fillets in 2015 was 0.124 ppm.The levels of contaminants from 2015, 2013 and 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.