Assessment Comments

Assessment is based on: (1) results of USGS ambient water quality monitoring conducted on the Maquoketa River near Spragueville, IA from January 2006 through December 2008 and (2) results of fish tissue monitoring conducted in 2005, 2006 and 2008 near Maquoketa for the U.S. EPA/IDNR (RAFT) fish tissue monitoring program.

Basis for Assessment

SUMMARY:  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 assessed (monitored) as “fully supported” based on results of chemical water quality monitoring by USGS conducted from 2006 through 2008.   Fish consumption uses remain assessed as “fully supported” based on fish contaminant monitoring in 2003, 2005, 2006, and 2008.   The sources of data for this assessment are (1) results of USGS ambient water quality monitoring conducted on the Maquoketa River near Spragueville, IA (USGS station 05418600) from January 2006 through December 2008 and (2) results of fish tissue monitoring conducted in 2005, 2006, and 2008 near Maquoketa for the U.S.  EPA/IDNR (RAFT) fish tissue monitoring program.  

EXPLANATION:  Assessments of support of the Class A1 uses were not developed due to the lack of water quality monitoring data for indicator bacteria in this river reach:  the USGS monitoring conducted near Spragueville did not include sampling for indicator bacteria.  

The Class B(WW1) aquatic life uses were assessed (monitored) as "fully supported" based on results of water quality monitoring by the U.S.   Geological Survey near Spragueville from 2006 through 2008.   No violations of state water quality criteria occurred in the 34 samples analyzed for dissolved oxygen, pH, ammonia, chlorpyrifos, DDE, and dieldrin.   The May 9, 2006 sample was analyzed for toxic metals; no violations of Class B(WW1) or human health criteria occurred for the 11 toxic metals analyzed.  

Fish consumption uses are assessed (monitored) as "fully supported" based on the 2005, 2006 and 2008 EPA/IDNR fish tissue (RAFT) samplings on the Maquoketa River northeast of Maquoketa.   This site has been sampled for whole-fish common carp since 1995 on an every-other-year basis as part of RAFT trend monitoring (due to a change in the design of the RAFT program, all of Iowa’s 10 trend sites were sampled in 2005 and 2006; all ten sites were then monitored as part of the 2008 RAFT sampling).   The whole-fish samples of common carp from these three years had generally low levels of the primary contaminants: mercury:  maximum of 0.136 ppm; total PCBs: maximum of 0.45 ppm; and technical chlordane: maximum of 0.059 ppm.   While results from these samplings show that levels of chlordane and mercury are well below levels of concern, the level of total PCBs in the sample of whole-fish common carp from the 2006 sampling (0.45 ppm) exceeds the 1 meal/week trigger level as defined in Iowa’s revised (2006) fish consumption advisory protocol.   The level of total PCBs in the 2005 whole-fish common carp sample was <0.09 ppm and the level of total PCBs in the 2008 whole-fish common carp sample was 0.105 ppm.  

The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of support of fish consumption uses in Iowa’s rivers and lakes.   The levels of total PCBs in the sample of whole-fish common carp collected in 2006 exceeded the 1 meal/week trigger level as defined in Iowa’s revised (2006) fish consumption advisory protocol.   According to IDNR’s assessment methodology, the single occurrence of contaminant above an advisory trigger level does not suggest impairment of the fish consumption uses but does suggest the need to conduct additional fish contaminant monitoring.   The IDNR/IDPH advisory protocol states that two consecutive samplings that show contaminant levels are above the trigger level in fillet samples are needed to justify issuance of an advisory.   The results for the  whole-fish sample from the 2006 sampling on the Maquoketa River did not warrant issuance of an advisory but did indicate the need to conduct additional monitoring to better define contaminant levels in fish from this river segment.   Additional monitoring in 2008, however, showed that levels of total PCBs were below the advisory trigger level (0.105 ppm).   If levels of total PCBs exceed the one meal/week advisory level, follow-up monitoring will be conducted to better determine (1) levels of PCBs in the edible portions (fillets) of fish in this river segment and (2) whether a 1 meal/week consumption advisory for PCBs needs to be issued.