Cedar River IA 02-CED-470

Assessment Comments

Assessment is based on results of (1) IDNR ambient city monitoring upstream from Cedar Falls from 2002-04 and (2) U.S. EPA/IDNR fish tissue (RAFT) monitoring in 1997.

Basis for Assessment

SUMMARY:  The Class B(WW) aquatic life uses were assessed (monitored) as "fully supported" based on results of ambient water quality monitoring from 2002-2004.   Fish consumption uses remain assessed (evaluated) as "fully supported" based on results of fish contaminant monitoring in 1997.   The sources of data for this assessment are (1) the results of monthly monitoring from January 2002 through December 2004 at the IDNR ambient city monitoring station located at upstream from Cedar Falls at the old highway 218 bridge at Cedar Falls (STORET station 10070005) and (2) the results of U.S.  EPA/IDNR fish tissue (RAFT) monitoring at Cedar Falls in September 1997.   Note:  this assessment is also used for the two adjacent downstream segments of the Cedar River:  IA 02-CED-0060-2 and IA 02-CED-0050-L.

EXPLANATION:  The Class B(WW) aquatic life uses were assessed (monitored) as "fully supported" based on results of monitoring from the IDNR ambient station at Cedar Falls from 2002 through 2004.   Monitoring at this station showed no violations of Class B(WW) water quality criteria for dissolved oxygen, pH, ammonia-nitrogen, toxic metals, and toxic organic compounds in the approximately 30 samples analyzed during this assessment period; no detected levels were reported in the seven samples from this station analyzed for pesticides.  

Fish consumption uses were assessed (evaluated) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring upstream from Cedar Falls in 1997.   Because these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is considered “evaluated” (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence).  

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.   This scenario, however, does not apply to the fish contaminant data generated from the 1997 RAFT sampling conducted in this assessment segment:  levels of all contaminants from this monitoring were below advisory trigger levels, thus suggesting the continued “full support” of fish consumption uses.