Mallard Slough
Marshall County, South Dakota194 acresView mapDirections
No nutrient or algae sampling on record from SD DANR for this lake.
Mallard Slough in Marshall County, South Dakota has water-quality measurements published by SD DANR, shown here as reported. Surface area: 194 acres.
Mallard Slough is a 194-acre lake in Marshall County, South Dakota.
Source: EPA Water Quality Portal sampling records, SD DANR. Methodology: how these readings are compared.
Swimming conditions
No readingNot rated
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Mallard Slough is safe to swim in today is a call for the South Dakota Department of Agriculture and Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Mallard Slough
These are the measurements SD DANR publishes for Mallard Slough, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. TSI undefined.
Ask about Mallard Slough
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
194 acres
Shoreline
3.2 mi
No bathymetric survey has been published for Mallard Slough, so its depth is not documented here.
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Frequently asked questions about Mallard Slough
Where is Mallard Slough?
- Mallard Slough is a lake in Marshall County, South Dakota. Its water-quality measurements are published by SD DANR and shown on this page as reported.
What is the water quality of Mallard Slough?
- Mallard Slough in Marshall County, South Dakota has water-quality measurements published by SD DANR, shown here as reported. Surface area: 194 acres.
Is Mallard Slough safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
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Where this data comes from
Measurements for Mallard Slough come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.