Chariton River IA 05-CHA-1308

Assessment Comments

Assessment is based on results of IDNR monthly water quality monitoring N of Centerville.

Basis for Assessment

Continue to assess support of the Class B(WW) uses as PS due to impacts of habitat alterations due to channelization.   Results of WQ montoring at the DNR WQ station N of Centerville, however, show no violations of Class B(WW) WQ criteria for either conventional or toxic pollutants in monthly sampling conducted over the October 95->September 95 assessment The Class C drinking water uses of this reach were assessed as FST due to levels of atrazine in 3 of the 24 samples collected over the two-year period that exceeded the atrazine MCL.   These samples were collected from July through Septemeber 1996 and ranged from 3.1 to 4.3 ug/l*.   See framework for determining degree of drinking water use support on page 3-44 of the supplement to the 1998 U.S.  EPA guidelines for Section 305(b) reporting for details on assessment methods.  Fish consumption uses were assessed as FS due to levels of all contaminants less than 1/2 FDA action levels in samples of fillets from channel catfish and white crappie collected from this reach for the 1996 RAFT program.   *Summary statistics for atrazine:  24 samples analyzed; mean= 2.1 ug/l; median=2.0 ug/l; 13% (3 of 24 samples) exceeded the MCL of 3.0 ug/l; range of 0.18 to 4.3 ug/l.   No violations of the nitrate MCL (10 mg/l as N) in the 36 samples over 3 years.  Follow-up monitoring is needed to determine the status of aquatic communities and habitats of this river.