Lake Capri
St. Francois County, Missouri112 acresView mapDirections
Missouri DNR publishes the water-quality measurements for Lake Capri. Here is what has been measured.
- Oligotrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 40 ft max depth
Lake Capri in St. Francois County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 16.3 ft visibility. Phosphorus: 5.7 µg/L. Chlorophyll-a (algae): 0.9 µg/L. Surface area: 112 acres.
Lake Capri is a 112-acre cold, clear oligotrophic lake in St. Francois County, Missouri with an estimated average depth of about 40 feet. Overall water quality is improving over recent sampling years. Compared to the 3 other monitored lakes in St. Francois County, Lake Capri ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2025-07-29. Methodology: how these readings are compared.
What Lake Capri is good for
From access and monitoring records, not editorial picks.
- Clear water16.3 ft of visibility
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Lake Capri is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Lake Capri is safe to swim in today is a call for the Missouri Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake Capri
These are the measurements Missouri DNR publishes for Lake Capri, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 16.3 ft down. Phosphorus 5.7 µg/L. Chlorophyll-a 0.9 µg/L. TSI 32.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 16.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 5.7µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 0.9µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 32 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Lake Capri
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Lake Capri typically sits around 81°F at the surface in August. Summer average is about 81°F. Usually warmest in Jul (about 83°F) and coldest in May (about 73°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (73°F) to its warmest (83°F).
Typical surface water temperature by month, from 60 field readings (2010–2024) via the EPA Water Quality Portal. See the full Lake Capri water temperature breakdown →
Lake Details
Max depth
~40 ft est.
Surface area
112 acres
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Missouri has not published bathymetry for Lake Capri.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Shoreline
2.1 mi
HydroLAKES / HydroSHEDS
Elevation
879 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Stays via Stay22
Stays near Lake Capri
Compare lakeside cabins, hotels, and vacation rentals near Lake Capri in St. Francois County, Missouri — 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 Lake Capri
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Fishing Lake Capri
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Improving4 years
Phosphorus
Worsening+0.41 µg/L/yr6 years
Chlorophyll-a
Improving-0.26 µg/L/yr5 years
Reservoir Info (USACE NID)
Lake Capri is a man-made reservoir impounded by the Lac Capri Dam (completed 1972), built primarily for recreation on the TR BIG RIVER; earth-type dam, 97 ft tall and 2,170 ft long.
- Surface area
- 112 ac
- Normal storage
- 2,828 ac-ft
- Max storage
- 3,541 ac-ft
- Drainage area
- 0.99 sq mi
- Hazard class
- High
- Owner
- TERRE DU LAC POA
Source: USACE National Inventory of Dams, NID ID MO30063 · Operator website · Matched by proximity (0.04 km)
EPA Impairment Status
Lake Capri is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life.
Source: EPA ATTAINS assessment unit MO_7297.00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Lake Capri under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Terre Du Lac South One Cell LagoonBonne Terre · 1.1 mi away · NPDES MO0057312Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in St. Francois County
Frequently asked questions about Lake Capri
Where is Lake Capri?
- Lake Capri is a lake in St. Francois County, Missouri. Its water-quality measurements are published by Missouri DNR and shown on this page as reported.
What is the water quality of Lake Capri?
- Lake Capri in St. Francois County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 16.3 ft visibility. Phosphorus: 5.7 µg/L. Chlorophyll-a (algae): 0.9 µg/L. Surface area: 112 acres.
Is Lake Capri safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Capri is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Lake Capri?
- Lake Capri typically sits around 81°F at the surface in August, from 60 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
How deep is Lake Capri?
- No published bathymetric survey covers Lake Capri, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 40 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 112 acres.
Explore Lake Capri across LakeQuality
More lakes in Missouri
Other Lakes in Missouri
Oligotrophic Lakes in Missouri
Where this data comes from
89 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC88 samples · 2020–2024 - Missouri Dept. of Natural Resources
MDNR1 sample · 2025
Analytical methods
- Depth, Secchi disk in meters
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- Nitrogen and Phosphorus, Total, Whole-water, Alkaline Persulfate Digest
Monitoring station identifiers (2)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)