ADBNet

Assessment Comments

Assessment is based on results of IDNR/UHL ambient water quality monitoring conducted in 2002 as part of TMDL development.

Basis for Assessment

[NOTE:  For the 2002 report, the previous waterbody segment for Little Rock River (IA 06-BSR-0060-0), which extended 46 miles from its mouth in Lyon County to the Iowa/Minnesota state line, was split into three subsegments:  (1) from mouth to Otter Creek near George (IA 06-BSR-0060-1), (2) Otter Creek to Argo Slough near Little Rock (IA 06-BSR-0060-2), and (3) (this one) Argo Slough to the Iowa Minnesota state line (IA 06-BSR-0060-3).   See assessment information found in subsegment IA 06-BSR-0060-2 for previous Section 305(b) assessments for the entire 46-mile reach.]

SUMMARY:  The Class B(LR) aquatic life uses are assessed (evaluated) as “fully supported” based on results of ambient chemical/physical water quality monitoring conducted near the Iowa/Minnesota state line by IDNR/UHL from March through November 2002 as part of TMDL monitoring (TMDL station 1; STORET station 11720001).  

EXPLANATION:  Results of chemical/physical water quality monitoring conducted from March through November 2002 by IDNR/UHL in support of TMDL development suggest relatively good water quality in this stream.   None of the 11 samples collected had levels of dissolved oxygen, pH, or ammonia-nitrogen that violated state water quality standards (these samples were not analyzed for toxic metals or pesticides).   The decision to consider this assessment as “evaluated” (lower confidence) versus “monitored” (higher confidence) is based on (1) the relatively few samples collected (11) and the relatively poor parameter coverage (i.e., no analysis of samples for toxic metals or pesticides).