Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Black Hawk Wildlife Area IA 04-RAC-1135

Sac County S9T86NR36W 2 mi S of Lake View.

Cycle
2020
Release Status
Final
Overall IR
4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend
Unknown
Created
9/4/2020 2:13:52 PM
Updated
10/15/2020 1:00:08 PM
Use Support
Class BLW
Aquatic Life - Lakes and wetlands
Partially Supported
Support Level
Partially Supported
Impairment Code
4c - Non-pollutant caused impairment. No TMDL needed.
Cause Magnitude
Moderate
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2002
Impairment Rationale
Adverse impacts on plant/animal communities
Data Source
Biological monitoring: Iowa DNR Wildlife
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Slight
Status
Continuing
Source
Agriculture
Source Confidence
Low
Cycle Added
2002
Impairment Rationale
Adverse impacts on plant/animal communities
Data Source
Biological monitoring: Iowa DNR Wildlife
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
High
Status
Continuing
Source
Agriculture
Source Confidence
N/A
Cycle Added
2008
Impairment Rationale
Adverse impacts on plant/animal communities
Data Source
Biological monitoring: Iowa DNR Wildlife
Class HH
Human Health -
Not Assessed
General Use
General Use water -
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BLW uses remain assessed (evaluated) as "partially supported" based on information from the IDNR Wildlife Bureau. All other designated uses are “not assessed.” This assessment is the same as that developed for previous assessment/listing cycles. 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 current assessment cycle

Assessment Explanation

Class BLW -

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. DNR 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. DNR typically does not consider waterbodies identified as "impaired" based on "evaluated assessments" as candidates for the state's Section 303(d) list.

Class HH - Fish Tissue sampling: No Data -

In general, Iowa wetlands are not managed for recreational fisheries; thus, fish contaminant monitoring is not typically conducted at these waterbodies.


Monitoring and Methods
Assessment Key Dates

None listed

Methods
120
Surveys of fish and game biologists/other professionals