Mortimer Slough
Mortimer Slough in Brookings County, South Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 139 acres.
- Area
- 139 acres
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Why Mortimer Slough has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Mortimer Slough, no water-quality sampling on record for this lake.
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by SD DANR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Mortimer Slough is a 139-acre lake in Brookings County, South Dakota.
Source: EPA Water Quality Portal sampling records, SD DANR, last sampled recent years. Grade methodology: LakeQuality methodology.
Watch Mortimer Slough water quality
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Swimming Safety
Not ratedElevated nutrients
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Mortimer Slough
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Trophic State Index: undefined.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) |
Where to stay near Mortimer Slough
Compare lakeside cabins, hotels, and vacation rentals near Mortimer Slough in Brookings County, South Dakota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Mortimer Slough
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 139 acres |
No bathymetric survey has been published for Mortimer Slough, so its depth is not documented here.
Fishing Mortimer Slough
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Frequently asked questions about Mortimer Slough
Where is Mortimer Slough?
- Mortimer Slough is a lake in Brookings County, South Dakota. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for Mortimer Slough?
- Mortimer Slough in Brookings County, South Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 139 acres.
Is Mortimer Slough safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Mortimer Slough is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Explore Mortimer Slough across LakeQuality
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Where this data comes from
Measurements for Mortimer Slough come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.