ADBNet

Assessment Comments

Assessment remains based on (1) information from the IDNR Wildlife Bureau and (2) results of watershed modeling by the IDNR Water Quality Bureau.

Basis for Assessment

[NOTES:  Prior to the 2002 cycle, the Waterbody ID number for this wetland was IA-WETLAND-31.   This wetland is not in the July 2003 version of the Iowa Water Quality Standards used for the 2006 assessment cycle but has been proposed for inclusion to the standards as a Class B(LW) waterbody.]

SUMMARY:  The aquatic life uses remain assessed (evaluated) as "not supported" due to hydrological modifications (flow alterations and channel degradation of the Missouri River) that adversely affect this wetland.   This type of impairment is appropriate for Category 4c of Iowa's Integrated Report (I.e.,  impairment due to a non-pollutant stressor).   This assessment is based on information from the IDNR Wildlife Bureau and results of watershed modeling by the IDNR Water Quality Bureau in 2002.   Fish consumption uses remain "not assessed."  This is the same assessment as that developed for the 2002 and 2004 assessment/listing cycles.

EXPLANATION:  The aquatic life uses remain assessed as "not supported" based on information from the Iowa DNR Wildife Bureau (see assessments developed for the 1998 and 2000 reporting cycles).   The watershed of this oxbow wetland was modeled, and modeling results indicate that sediment delivery to the wetland from the watershed is very low.   The local DNR biologist indicates that the Missouri River does not breach the original high bank, but occasionally (10 -15 years) flood waters do enter the wetlands directly adjacent to the river; these flood events, however, do not reach Round Lake.   This wetland does, however, continue to suffer from hydrologic modification and the related problems of lowered water tables in the Missouri River floodplain and lowered water levels in the river's floodplain wetlands.   The assessment category for this wetland of "evaluated" indicates that the assessment is based largely 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" due to the lack of fish contaminant monitoring at this wetland.   In general, Iowa wetlands are not managed for recreational fisheries; thus, fish contaminant monitoring is not typically conducted at these waterbodies.