Assessment Comments

Assessment is based on (1) results of USGS ambient monitoring near Spragueville in 2004 and (2) EPA/IDNR fish tissue (RAFT) monitoring NE of Maquoketa in 2003.

Basis for Assessment

SUMMARY:  The Class A (primary contact recreation) uses are “not assessed” due to the lack of information upon which to base an assessment.   The Class B(WW) aquatic life uses are assessed (evaluated) as “fully supported” based on results of limited chemical water quality monitoring by USGS conducted in 2004.   Fish consumption uses are assessed as “fully supported” based on fish contaminant monitoring in 2003.   The sources of data for this assessment are (1) results of USGS ambient water quality monitoring conducted on the Maquoketa River near Spragueville, IA from March to September 2004 and (2) results of fish tissue monitoring in 2003 near Maquoketa conducted for the U.S.  EPA/IDNR (RAFT) fish tissue monitoring program.  

EXPLANATION:  Assessments of support of the Class A uses were not developed due to the lack of water quality monitoring data for this river reach.  

The Class B(WW) aquatic life uses were assessed (evaluated) as "fully supported" based on results of water quality monitoring by the U.S.  Geological Survey near Spragueville in 2004.   No violations of state water quality criteria occurred in the nine samples analyzed for dissolved oxygen, pH, ammonia, chlorpyrifos, DDE, and dieldrin.   Although these results indicate “full support” of the aquatic life uses of this river segment, the number of samples is relatively low and does not meet IDNR guidelines for developing a “monitored” (i.e., higher confidence) assessment.   Thus, the assessment type is considered “evaluated” (lower confidence).

Fish consumption uses are assessed as "fully supported" based on the 2003 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.   The whole-fish sample of common carp had generally low levels of the primary contaminants:  mercury: 0.07 ppm; total PCBs: 0.333 ppm; and technical chlordane:< 0.03 ppm.   While results from the 2003 sampling 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 exceeds the 1 meal/week trigger level as defined in Iowa’s revised (2006) fish consumption advisory protocol.  

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.   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, 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.   Although this scenario does not apply to the fish contaminant data generated from the 2003 RAFT sampling conducted in this assessment segment, levels of contaminant are sufficiently high for concern and justify follow-up monitoring.   The level of total PCBs in the sample of whole-fish common carp collected in 2003 exceeds 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 2003 sampling on the Maquoketa River does not warrant issuance of an advisory but does indicate the need to conduct additional monitoring to better define contaminant levels in fish from this river segment.   Thus, follow-up monitoring will be conducted in 2006 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.