Black Hawk Wildlife Area IA 04-RAC-1135

Assessment Comments

Assessment remains based on information from the IDNR Wildlife Bureau.

Basis for Assessment

Notes:  This publicly-owned waterbody was added to the list of Iowa wetlands in 1994 at the suggestion of the DNR Wildlife Bureau.   For the 2002 report, the waterbody identification number for this wetland was changed from "IA-WETLAND-50" to "IA 04-RAC-00477-L."  This wetland was not in the 2010 version of the Iowa Water Quality Standards (Surface Water Classification) and is thus classified only for "general uses."  This wetland however, has been proposed for inclusion to the standards as a Class B(LW) waterbody.   Due to the stated impacts from purple loosestrife, this waterbody was moved to Category 4c (impaired; TMDL not required) of Iowa's 2008 Integrated Report.   This waterbody remains in Category 4c of the 2010 Integrated Report.  

SUMMARY:  Continued to assess (evaluate) support of the aquatic life uses as "partially supported."  Other beneficial uses remain "not assessed."  This assessment is the same as that developed for previous assessment/listing cycles.  

EXPLANATION:  The 2000 assessment of support of the aquatic life uses ("partially supported") was reviewed and approved by the DNR Wildlife Bureau in 2002.   According to the local DNR Wildlife Biologist (Mahn), this wetland remains impaired by purple loosestrife.   Biological control of this exotic plant species does not appear to be working; the native wetland edge vegetation is slowly being replaced by purple loosestrife.   There are no data, however, to verify that the wetland is receiving excessive amounts of sediment.   This wetland area also suffers from water level fluctuations in the past which may influence judgment on how much sediment is present in the wetland.   The assessment category for this wetland of "evaluated" indicates that the assessment is based primarily on "best professional judgment."  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 judgment]) and thus have relatively lower confidence.   IDNR typically 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.