South Fork Chariton River IA 05-CHA-1327

Assessment Comments

Assessment is based on results of monitoring conducted by ACOE.

Basis for Assessment

Changed the assessment of support of Class B(LR) uses from PS to "not assessed":  no biological information available.   Monitoring is needed to determine the status of aquatic communities and habitats.   Monitoring conducted by the U.S.  Army Corps of Engineers from April through September 1997 show no violations of Class B(LR) WQ criteria for DO (2 samples), pH (2 samples), or ammonia (10 samples).   This monitoring showed that 3 of 10 samples had levels of atrazine that exceeded the MCL of 3 ug/l, with two of the three samples collected in June 1997.   The average level of atrazine in the 10 samples was 5.8 ug/l; the median was 1.05 ug/l; levels of atrazine ranged from 0.12 to 30.2 ug/l.   All levels of alachlor were below the MCL of 2.0 ug/l.   Levels of cyanazine ranged from 0.04 to 8.3 ug/l, with an average of 1.56 ug/l.   Although the S.Fk.  Chariton River is not designated for Class C drinking water uses, the river is tributary to Rathbun Lake, a Class C waterbody.   A summary of the 1997 ACOE sampling is available.