Mill Creek Lake
Mill Creek Lake in Calvert County, Maryland is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3 ft visibility.
- Clarity
- 3 ft
- Trend
- ↓ Declining
Why Mill Creek Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: 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 Mill Creek Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
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 your state environmental agency and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Mill Creek Lake is a lake in Calvert County, Maryland. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2022-10-20. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Mill Creek Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 3 ft of visibility. Trophic State Index: 62.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 62 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Mill Creek Lake
Compare lakeside cabins, hotels, and vacation rentals near Mill Creek Lake in Calvert County, Maryland — 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 Mill Creek Lake
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Fishing Mill Creek Lake
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.3 m/yr | 2 |
Nearby Lakes in Calvert County
Frequently asked questions about Mill Creek Lake
What is the water quality grade for Mill Creek Lake?
- Mill Creek Lake in Calvert County, Maryland is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3 ft visibility.
Is Mill Creek Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Mill Creek Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Explore Mill Creek Lake across LakeGrade
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Other Lakes in Maryland
Eutrophic Lakes in Maryland
Where this data comes from
132 measurements from 4 monitoring stations, 2021–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples132 samples · 2021–2022
Monitoring station identifiers (4)
Grade thresholds come from the U.S. EPA National Lakes Assessment 2022 Technical Support Document (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Data Sources
Water quality data from the EPA Water Quality Portal
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2022-10-20
Monitoring stations: 4