Muskrat Slough IA 01-WPS-339

Assessment Comments

Assessment based on information from the IDNR Wildlife Bureau.

Basis for Assessment

SUMMARY:  Continued to assess (evaluate) support of the Class B(LW) aquatic life uses as "partially supported."  Fish consumption uses remain "not assessed."  This is the same assessment as that developed for the 2002 reporting cycle.

EXPLANATION:  The previous (2000) assessment of support of the Class B(LW) uses ("partially supported") was reviewed and approved by the DNR Wildlife Bureau in 2002.   According to the local DNR Wildlife Biologist (Sheets), excessive siltation has choked off and eliminated an estimated 30 acre region in the north-central and northeast segments of the wetland.   Repeated ditch cleaning has been necessary to maintain marsh management capabilities.   Much of the emergent marsh vegetation is reverting to poplar, willow, and silver maple.   Extensive brush cutting efforts and herbicide treatment have been necessary over the past 15 years to keep woody invasion in check.   The assessment category for this wetland of "evaluated" indicates that the assessment is based entirely on "best professional judgement."  In terms of Section 305(b) reporting, "monitored assessments" are based primarily on recent, site-specific ambient monitoring data and thus have relatively high confidence.   IDNR considers waterbodies identified as "impaired" based on "monitored assessments" as candidates for the state's Section 303(d) list.   "Evaluated assessments" are those based on data older than five years or other than site-specific ambient monitoring data (e.g., questionnaire surveys of fish and game biologists [=best professional judgement]) and thus have relatively low confidence.   IDNR does not consider waterbodies identified as "impaired" based on "evaluated assessments" as candidates for the state's Section 303(d) list.   Fish consumption uses remain "not assessed."  In general, Iowa wetlands are not managed for recreational fisheries; thus, fish contaminant monitoring is not typically conducted at these waterbodies.