Assessment Comments
Assessment is based on: (1) results of fish contaminant monitoring conducted near the Volga River Recreation Area in 2001 and 2005 as part of U.S. EPA/IDNR fish contaminant (RAFT) monitoring, (2) results of IDNR/UHL monitoring at TMDL site 36 in 2000, and (3) results of IDNR/Fisheries Bureau biological monitoring in 2000.
Basis for Assessment
[Note: Prior to the current (2008) Section 305(b) cycle, this stream segment was designated only for Class B(WW) aquatic life uses. Due to changes in Iowa’s surface water classification that were approved by U.S. EPA in February 2008 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf), and due to the completion of a Use Attainability Analysis in 2007, this segment is also now designated for Class A1 (primary contact recreation) uses. This stream segment remains designated for aquatic life uses (now termed Class B(WW1) aquatic life uses). This stream segment also remains identified as an “HQR” (high quality resource) water. Thus, for the current (2008) assessment, the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW1) water quality criteria.]
SUMMARY: The Class A1 (primary contact recreation) uses are "not assessed" due to lack of information on levels of indicator bacteria in this river segment. The Class B(WW1) aquatic life uses remain assessed (evaluated) as "fully supported" based on (1) the lack of violations of state water quality criteria for pH and dissolved oxygen in the nine samples collected in 2000 from the TMDL monitoring station on the Volga River near at White Pine Forrest Preserve upstream from Volga (Site 36) and (2) results of IDNR/Fisheries Bureau biological monitoring in 2000. Fish consumption uses are assessed (monitored) as “partially supported” based on fish contaminant monitoring in 2001 and 2005. The sources of data for this assessment include (1) results of fish contaminant monitoring conducted near the Volga River Recreation Area in 2001 and 2005 as part of U.S. EPA/IDNR fish contaminant (RAFT) monitoring, (2) results of IDNR/UHL monitoring at TMDL site 36 in 2000, and (3) results of IDNR/Fisheries Bureau biological monitoring in 2000.
EXPLANATION: The Class A1 (primary contact recreation) uses were "not assessed" due to lack of information on levels of indicator bacteria in this river segment.
The Class B(WW1) aquatic life uses remain assessed (evaluated) as "fully supported." This assessment was based on data collected in 2000 as part of a DNR Fisheries stream sampling project: Manchester research station. A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the Fisheries sampling data. The biological metrics are based on the numbers and types of fish species that were collected in the stream sampling reach. The biological metrics were combined to make a fish community index of biotic integrity (F-IBI). The index ranks the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2000 evaluated Fish IBI = 79 (excellent). The aquatic life use support was assessed (evaluated) as Fully Supporting (=FS), based on a comparison of the F-IBI score with biological assessment criteria established for previous Section 305(b) reports. The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2001.
Fish consumption uses are assessed (monitored) as “partially supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring near the Volga State Recreation Area in 2001 and in 2005. 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. Prior to 2006, IDNR used action levels published by the U.S Food and Drug Administration to determine whether consumption advisories should be issued for fish caught as part of recreational fishing in Iowa. In an effort to make Iowa’s consumption more compatible with the various protocols used by adjacent states, the Iowa Department of Public Health (IDPH), in cooperation with Iowa DNR, developed a risk-based advisory protocol. This protocol went into effect in January 2006 (see http://www.iowadnr.gov/fish/news/consump.html for more information on Iowa’s revised fish consumption advisory protocol). Because the revised (2006) protocol is more restrictive than the previous protocol based on FDA action levels; fish contaminant data that previously suggested “full support” may now suggest either a threat to, or impairment of, fish consumption uses. This scenario applies to the fish contaminant data generated from the RAFT sampling conducted in this segment of the Volga River: levels of mercury in samples of smallmouth bass from consecutive samplings exceeded advisory trigger levels, thus suggesting the need for a consumption advisory. According to IDNR’s assessment methodology, the existence of a one-meal-per-week consumption advisory indicates that fish consumption uses should be assessed as “partially supported”.
For the 2001 RAFT sampling, the composite samples of fillets of smallmouth bass contained 0.326 ppm of mercury. The level of mercury in the sample of 2005 composite sample smallmouth bass fillets was 0.545 ppm. According to the IDNR/IDPH advisory protocol, if two consecutive samplings show that contaminant levels are above the trigger level in fillet samples, issuance of a consumption advisory is justified. This advisory was issued by IDNR and IDPH in January 2006 and covers the segments of the Volga River upriver from the county road C2W bridge at Volga in western Clayton County.
