Allen Green Refuge Marsh IA 02-ICM-620
Des Moines County S29T72NR1W 8 mi. E of Mediapolis.
- 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
- 7/20/2020 2:46:23 PM
- Updated
- 7/20/2020 2:50:21 PM
The Class BLW lake/wetland aquatic life uses remain assessed (evaluated) as "partially supported" due to de-watering from an adjacent drainage ditch. This type of impairment is appropriate for Category 4c of Iowa's Integrated Report (i.e., impairment due to a non-pollutant stressor). All other designated uses are “not assessed”. This is the same assessment as used for previous assessment/listing cycles.
According to the DNR Wildlife Biologist (Ohde), the nutrient impact identified for this wetland in previous Section 305(b) assessments no longer exists:the cattle feedlot virtually on the banks of the wetland has now been abandoned for several years. The impacts from hydrological modification caused by the adjacent drainage ditch, however remain. This ditch has completely altered the natural hydrology of the wetland. The ditch is lower than the bottom of the wetland basin and tends to speed drying of the basin such that the wetland has been altered from a mostly open semi-permanent wetland to a seasonal wetland dominated by perennial emergent vegetation. Water is pumped into the wetland in the fall for use by migratory waterfowl, but the rate of water loss to the drainage ditch makes year-round pumping to restore wetland function (1) impossible given current pumping capabilities and (2) cost prohibitive. The assessment category for this wetland of "evaluated" indicates that the assessment is based entirely 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 low confidence. DNR 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.
None listed