Walker Branch IA 05-CHA-1329
mouth (S36 T70N R20W Wayne Co.) to confluence with S. Fk. Walker Branch in SE 1/4 S26 T70N R20W Wayne Co.
Assessment Comments
Basis for Assessment
Did not develop an assessment of support of the Class B(LR) aquatic life uses due to lack of information. Results of U.S. Army Corps of Engineers monitoring in 1997 near Confidence as part of a Rathbun Lake watershed study showed that none of the 5 samples collected between May and August 1997 exceeded the Class B(LR) WQ criteria for ammonia. These data, however, are not sufficient for developing an assessment of use support. Although not designated for Class C drinking water uses, the ACOE monitoring showed that 2 of 5 samples had levels of atrazine that exceeded the MCL of 3.0 ug/l. The average level of atrazine in the five samples was 4.12 ug/l; the median level was 2.21 ug/l, with a range of 1.47 to 8.75 ug/l. Similar to the other sites sampled as part of this study, levels of alaclor were all below the MCL of 2.0 ug/l, and levels of cyanazine exceeded the MCLG of 1.0 ug/l. Although not designated for drinking water uses, Walker Branch is tributary to Rathbun Lake which is designated for Class C drinking water uses. A summary of the ACOE monitoring in 1997 is available.