Where is Lake Marseilles-Terre du Lac Lakes?

Lake Marseilles-Terre du Lac Lakes 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 temperature of Lake Marseilles-Terre du Lac Lakes?

Lake Marseilles-Terre du Lac Lakes typically sits around 81°F at the surface in August, from 12 EPA Water Quality Portal field readings (2013–2020). That is a typical value for the month, not a live reading.

How deep is Lake Marseilles-Terre du Lac Lakes?

No published bathymetric survey covers Lake Marseilles-Terre du Lac Lakes, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 41 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 56 acres.

Lake Marseilles-Terre du Lac Lakes

St. Francois County, Missouri56 acresView map Directions

Missouri DNR publishes the water-quality measurements for Lake Marseilles-Terre du Lac Lakes. Here is what has been measured.

Clarity

14.1 ft

Clearer than most

Secchi · sampled 2020

Phosphorus

7.4 µg/L

Less phosphorus than most

Measured by Missouri DNR

Chlorophyll-a

2.4 µg/L

Less algae than most

Measured by Missouri DNR

Water temp

~81°F

Typical for Aug · EPA WQP

Max depth

~41 ft est.

GLOBathy model

Area

56 acres

Surface area

Mesotrophic
Impaired · Algal growth
41 ft max depth
Limited data

See the measurements Directions Where to stay

Lake Marseilles-Terre du Lac Lakes in St. Francois County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 14.1 ft visibility. Phosphorus: 7.4 µg/L. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 56 acres.

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Lake Marseilles-Terre du Lac Lakes is a 56-acre mesotrophic lake in St. Francois County, Missouri with an estimated average depth of about 41 feet. Overall water quality is improving over recent sampling years. Compared to the 3 other monitored lakes in St. Francois County, Lake Marseilles-Terre du Lac Lakes ranks #2 for water quality.

Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2020-08-31. Methodology: how these readings are compared.

What Lake Marseilles-Terre du Lac Lakes is good for

From access and monitoring records, not editorial picks.

Clear water14.1 ft of visibility

Swimming conditions

Readings only

Limited data

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 Marseilles-Terre du Lac Lakes is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen). Check local advisories before you swim.

Whether Lake Marseilles-Terre du Lac Lakes 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.

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Water quality measurements for Lake Marseilles-Terre du Lac Lakes

These are the measurements Missouri DNR publishes for Lake Marseilles-Terre du Lac Lakes, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.

Good clarity, visible to about 14.1 ft. Phosphorus 7.4 µg/L. Chlorophyll-a 2.4 µg/L. TSI 37.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)	14.1ft	Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer.
Total phosphorus	7.4µg/L	Good GoodFairPoor
Chlorophyll-a (algae)	2.4µg/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.	37	Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic

Moderate nutrients, good water quality

Ask about Lake Marseilles-Terre du Lac Lakes

Answers come straight from the public measurements and survey records on this page.

Water Temperature

Lake Marseilles-Terre du Lac Lakes 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 Jun (about 79°F). These are typical values by month — not a live reading.

Jan

Feb

Mar

Apr

May

79°

Jun

83°

Jul

81°

Aug

Sep

Oct

Nov

Dec

Column height runs from this lake’s coldest month (79°F) to its warmest (83°F).

Typical surface water temperature by month, from 12 field readings (2013–2020) via the EPA Water Quality Portal. See the full Lake Marseilles-Terre du Lac Lakes water temperature breakdown →

Lake Details

Max depth

~41 ft est.

Surface area

56 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 Marseilles-Terre du Lac Lakes.

Lake Size & Watershed

Watershed (drainage) area

1 sq mi

HydroLAKES / HydroSHEDS

Shoreline

1.5 mi

HydroLAKES / HydroSHEDS

Elevation

863 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.

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Stays near Lake Marseilles-Terre du Lac Lakes

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Fishing Lake Marseilles-Terre du Lac Lakes

→ Lake Marseilles-Terre du Lac Lakes fishing regulations (limits, seasons, special rules)

Water Quality Trend: Improving

Based on 6 years of monitoring (2020–2025).

Water clarity
Improving
4 years
Phosphorus
Worsening
+0.41 µg/L/yr6 years
Chlorophyll-a
Improving
-0.26 µg/L/yr5 years

See year-by-year chart →

Reservoir Info (USACE NID)

Lake Marseilles-Terre du Lac Lakes is a man-made reservoir impounded by the Lac Marseilles Dam (completed 1971), built primarily for recreation on the TR-BIG RIVER; earth-type dam, 69 ft tall and 1,185 ft long.

Surface area: 56 ac
Normal storage: 1,900 ac-ft
Max storage: 1,900 ac-ft
Drainage area: 0.59 sq mi
Hazard class: High
Owner: TERRE DU LAC POA

Source: USACE National Inventory of Dams, NID ID MO30282 · Operator website · Matched by proximity (0.1 km)

EPA Impairment Status

Lake Marseilles-Terre du Lac Lakes is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).

Causes of impairment

Algal growthNutrients (phosphorus, nitrogen)

Designated uses not supporting: Aquatic life.

Source: EPA ATTAINS assessment unit MO_7614.00 · Official waterbody report

Regulated Pollution Sources Nearby

5 EPA-permitted facilities operate within about 5 miles of Lake Marseilles-Terre du Lac Lakes under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.

Terre Dulac Oxidation Ditch Wwtp
Bonne Terre · 0.6 mi away · NPDES MO0095311
Recent violation
West St. Francois R-Iv Schools Wwtp
Park Hills · 2.1 mi away · NPDES MO0125083
Recent violation
Leadwood Wwtp
Leadwood · 3 mi away · NPDES MO0104256
Recent violation
St. Francois County Environmental Corp
Park Hills · 4.5 mi away · NPDES MO0108774
Imperial
Bonne Terre · 4.7 mi away · NPDES MONX00962

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

Lake Capri16.3 ft clear · Oligotrophic0.4 miView →Lac Carmel—View →Lake Primrose—View →Timberline Lakes14.3 ft clear · Oligotrophic8 miView →Hemitite Lake1.1 ft clear · Hypereutrophic11.4 miView →Iron Mountain Lake—View →

Frequently asked questions about Lake Marseilles-Terre du Lac Lakes

Where is Lake Marseilles-Terre du Lac Lakes?: Lake Marseilles-Terre du Lac Lakes 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 Marseilles-Terre du Lac Lakes?: Lake Marseilles-Terre du Lac Lakes in St. Francois County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 14.1 ft visibility. Phosphorus: 7.4 µg/L. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 56 acres.
Is Lake Marseilles-Terre du Lac Lakes safe to swim in?: Nutrient and algae readings are not a swimming clearance. Lake Marseilles-Terre du Lac Lakes is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Lake Marseilles-Terre du Lac Lakes?: Lake Marseilles-Terre du Lac Lakes typically sits around 81°F at the surface in August, from 12 EPA Water Quality Portal field readings (2013–2020). That is a typical value for the month, not a live reading.
How deep is Lake Marseilles-Terre du Lac Lakes?: No published bathymetric survey covers Lake Marseilles-Terre du Lac Lakes, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 41 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 56 acres.

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Marion Reservoir Port Perry Lake North Arm Port Perry Lake South Arm Port Perry Lake

Where this data comes from

20 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

Univ. of Missouri, ColumbiaUMC20 samples · 2020

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

Monitoring station identifiers (1)

UMC-7614/0.1

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.