Assessment Comments
Assessment based on (1) special study of low levels of dissolved oxygen conducted by Wisconsin DNR in summer 1997 and 1998, (2) results of U.S. EPA/IDNR fish tissue monitoring in 2000, and (3) a 1999 USGS publication on the ecological health of the Upper Mississippi River system.
Basis for Assessment
SUMMARY: The Class A (primary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment. The Class B(WW) aquatic life uses remain assessed (evaluated) as "fully supporting / threatened" based on monitoring in 1997 that showed low levels of dissolved oxygen in this river segment. Fish consumption uses remain assessed (monitored) as "fully supported" based on fish contamiant monitoring in 2000. The sources of data used for this assessment are (1) Sullivan and Endris (1998), (2) results of U.S. EPA/DNR fish tissue (RAFT) monitoring in 2000 downstream from Guttenberg, and (3) a report on ecological status and trends of the UMR by USGS (1999)
EXPLANATION: An assessment of support of the Class A (primary contact recreation) uses was not developed due to lack of sufficient data on levels of indicator bacteria in this river reach.
The Class B(WW) uses remain assessed (evaluated) as "fully supporting / threatened" based on the 1997 study of dissolved oxygen levels by Sullivan and Endris (1998) of the Wisconsin DNR (see assessment for the 1998 report). The study by Sullivan and Endris (1998) showed low levels of dissolved oxygen in the main channel of the Mississippi River during late June/early July 1997 during a period of high water temperatures and low river flow from Pool 9 downriver to Pool 12; follow-up investigation suggested that these low levels of dissolved oxygen were due to high densities of zebra mussels in this river reach. However, because the data from Sullivan and Endris (1998) are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is changed from "monitored" (indicating an assessment with relatively high confidence) to "evaluated" (indicating an assessment with relatively low confidence).
Chapter 16 of the USGS (1999) report ("Assessments and forecasts of the ecological health of the Upper Mississippi River System floodplain reaches"), identifies Pools 1-13 as a "moderately impacted" ecosystem with declining structural diversity and threats to native mussels from zebra mussels. They note, however, that the ability of this river reach to recover from disturbances has been demonstrated by improving populations of aquatic macroinvertebrates and aquatic vegetation. These authors suggests that the recovery of these aquatic communities is, at least in part, related to improved water quality over the last 25 years due to national clean water programs.
Fish consumption uses are assessed (monitored) as "fully supported" based on results of U.S. EPA/DNR fish tissue (RAFT) monitoring in 2000 downstream from Guttenberg. This sampling showed that levels of contaminants in composite samples of fillets from channel catfish and smallmouth bass were less than ½ the respective FDA action levels and DNR levels of concern. For more information on results of fish contaminant monitoring in this river segment, see the assessment developed for the 2000 report.
