Assessment Comments
Assessment is based on results of (1) USGS/NAWQA monitoring of water quality from 2000-02, (2) USGS/NAWQA fish contaminant monitoring in 19095, and (3) occurrence of fish kills in the watershed.
Basis for Assessment
SUMMARY: The Class B(WW) aquatic life uses remain assessed (evaluated) as "fully supported / threatened" based on this history of repeated fish kills in this watershed. The fish consumption uses are assessed (evaluated) as “fully supported" based on results of fish contaminant monitoring in 1995. The sources of information for this assessment include (1) results of monitoring conducted on South Fork Iowa River 2 miles northeast of New Providence from January 2000 through August 2002 by USGS as part of the National Water Quality Assessment Program (NAWQA) (eastern Iowa river basins study unit, station 05451210), (2) results of fish contaminant monitoring conducted as part of the USGS NAWQA program near New Providence in 1995 and (3) the history of fish kills in this watershed.
EXPLANATION: The assessment of support of the Class B(WW) uses for the 2004 reporting cycle is based (1) on the USGS/NAWQA monitoring near New Providence that showed (1) no violations of Class B(WW) water quality criteria for pH, dissolved oxygen, or ammonia-nitrogen in the 32 samples collected from January 2000 through August 2002 and (2) no violations of the Class B(WW) chronic water quality criterion for pesticides in the 31 samples analyzed during this period. Although these results suggest full support of aquatic life uses, the watershed of the South Fork Iowa River has a history of repeated fish kills, often in the upper reaches of the stream. Despite the lack of fish kills in this lower reach of the South Fork Iowa River during 2000-2002 assessment period, fish kills continue to occur in this watershed (for example, a fish kill attributed to animal waste occurred in the headwaters of this stream on September 6, 2001). Thus, based on results of USGS monitoring and on the history of fish kills in this watershed, the Class B(WW) aquatic life uses remain assessed as "fully supported / threatened."
Fish consumption uses are assessed (evaluated) as “fully supported” based on results of fish contaminant monitoring conducted near New Providence in 1995 as part of the USGS NAWQA program (see assessments for the 1998 report for more information). However, because these data 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 lower confidence).
