Mccormack Lake is a 10-acre cold, clear oligotrophic lake in Oregon County, Missouri. Water quality is graded A based on 3 sampling years through 2020.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2020-09-10. Grade methodology: LakeGrade methodology.
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Good clarity, visible to about 11.7 ft. Phosphorus level: 6 µg/L. Chlorophyll-a: 3 µg/L. Trophic State Index: 38.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.7 ft | B |
| Phosphorus | 6 µg/L | A |
| Chlorophyll-a (Algae) | 3 µg/L | A |
| Trophic State Index (TSI) | 38 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 10 acres |
Where to stay near Mccormack Lake
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Fishing Mccormack Lake
Water Temperature
Mccormack Lake averages about 72°F at the surface in summer, usually warmest in Jul (about 79°F) and coldest in Jun (about 68°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 8 field readings (2013–2020) via the EPA Water Quality Portal. See the full Mccormack Lake water temperature breakdown →
Location
County Ranking
Ranked #1 of 1 lakes in Oregon County
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Other Grade A Lakes in Missouri
Ripley County · Clarity: 13.6 ft
Iron County · Clarity: 13.1 ft
Washington County · Clarity: 11.1 ft
St. Francois County · Clarity: 16.3 ft
St. Francois County · Clarity: 14.1 ft
St. Francois County · Clarity: 14.3 ft
Oligotrophic Lakes in Missouri
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Reservoir Info (USACE NID)
Mccormack Lake is a man-made reservoir impounded by the Mccormack Dam (completed 1937), built primarily for recreation on the MC CORMACK HOLLOW; earth-type dam, 27 ft tall and 366 ft long.
- Surface area
- 10 ac
- Normal storage
- 88 ac-ft
- Max storage
- 148 ac-ft
- Drainage area
- 4 sq mi
- Hazard class
- Significant
- Owner
- USDA FS
Source: USACE National Inventory of Dams, NID ID MO30004 · Operator website
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2020-09-10
Monitoring stations: 1