Jackson Creek IA 05-CHA-1332
mouth (S1 T70N R21W Wayne Co.) to confluence with unnamed tributary in S12 T68N R21W Wayne Co.
Assessment Comments
Basis for Assessment
Too few data were available from ACOE monitoring conducted in 1997 as part of a Rathbun L. watershed study to assess support of the Class B(LR) aquatic life uses. None of the 7 samples collected between May and September 1997 contained levels of ammonia that exceeded the Class B(LR) WQ criterion. However, this is relatively little information on which to base an assessment. Although Jackson Creek is not designated for Class C drinking water uses, this stream is tributary to Rathbun Lake, a Class C waterbody. ACOE sampling for agricultural pesticides from May to Sept. 1997 showed that 2 of 7 samples exceeded the MCL for atrazine; both samples were collected in June (3.88 and 16.7 ug/l). The average level of atrazine was 3.99 ug/l, median = 1.99 ug/l, and levels ranged from 0.51 to 16.7 ug/l. Levels of alachlor in all samples were less than the 2.0 ug/l MCL. Other pesticides were sampled for (e.g., metolachlor and cyanazine). Cyanazine concentrations in June were well above the MCLG of 1.0 ug/l; the Iowa Water Quality Standards (1994) do not contain a Class C criterion for cyanazine. A summary of the ACOE sampling in the Rathbun Lake watershed is available.