Where is Lake Marseilles-Terre du Lac Lakes?

Lake Marseilles-Terre du Lac Lakes is a lake in St. Francois County, Missouri. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.

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

Excellent

Clarity, phosphorus, and algae all sit in the cleanest band for this region.

Water temp

~81°F

Typical for Aug · EPA WQP

Clarity

14.1 ft

Secchi · sampled 2020

Max depth

~41 ft est.

GLOBathy model

Level

No gauge

Trend

Improving

6 years of samples

Mesotrophic
Impaired · Algal growth
#2 of 4 in the county
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 a water quality grade of A (Excellent). Water clarity: 14.1 ft visibility. Phosphorus: 7.4 µg/L. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 56 acres.

Clarity: 14.1 ft
Typical in August: 81°F
Max depth: ~41 ft est.
Area: 56 acres
Type: Mesotrophic
Phosphorus: 7.4 µg/L
Chlorophyll-a: 2.4 µg/L
Trend: ↑ Improving

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Watch Lake Marseilles-Terre du Lac Lakes’s letter

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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. Water quality is graded A based on 2 sampling years through 2020. 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. Grade methodology: LakeQuality methodology.

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 Safety

Grade only

Limited data

Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.

The A is nutrients and algae, 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.

Compare the safest swimming lakes near St. Louis →

Get alerts for Lake Marseilles-Terre du Lac Lakes →

Water Quality Grade: A (Excellent)

Good clarity, visible to about 14.1 ft. Phosphorus 7.4 µg/L. Chlorophyll-a 2.4 µg/L. TSI 37. The letter is not a swimming clearance.

Metric	Value	Grade
Water Clarity (Secchi Depth)	14.1 ft	Not graded
Phosphorus	7.4 µg/L	Good
Chlorophyll-a (Algae)	2.4 µg/L	Good
Trophic State Index (TSI)	37	Mesotrophic

Moderate nutrients, good water quality

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

—

Jun

79°

Jul

83°

Aug

81°

Sep

—

Oct

—

Nov

—

Dec

—

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

Characteristic	Value
Maximum Depth	~41 ft est.
Average Depth	~13 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

Shoreline

1.5 mi

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.

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 data (2020-2025).

Metric	Trend	Change/Year	Years
Water Clarity	↑ Improving	+0.098 m/yr	4
Phosphorus	↓ Declining	+0.41 µg/L/yr	6
Chlorophyll-a	↑ Improving	-0.26 µg/L/yr	5

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)

Source: EPA ATTAINS assessment unit MO_7614.00 · Official waterbody report · Matched by proximity (0.31 km)

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.

County Ranking

Ranked #2 of 4 lakes in St. Francois County

Nearby Lakes in St. Francois County

ALake Capri16.3 ft clear · Oligotrophic0.4 miView →NRLac Carmel—View →NRLake Primrose—View →ATimberline Lakes14.3 ft clear · Oligotrophic8 miView →FHemitite Lake1.1 ft clear · Hypereutrophic11.4 miView →NRIron 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. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Marseilles-Terre du Lac Lakes?: Lake Marseilles-Terre du Lac Lakes in St. Francois County, Missouri has a water quality grade of A (Excellent). 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?: The A is nutrients and algae, 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.

Explore Lake Marseilles-Terre du Lac Lakes across LakeQuality

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Other Grade A Lakes in Missouri

Lake Shayne-Terre du Lac Lakes

Washington County · 11.1 ft

Goose Creek Lake

Ste. Genevieve County · 9.9 ft

Council Bluff Lake

Iron County · 13.1 ft

Lake Wauwanoka

Jefferson County · 12.9 ft

Port Perry Lake North Arm

Perry County · 7.4 ft

Port Perry Lake South Arm

Perry County · 9.5 ft

Mesotrophic Lakes in Missouri

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

Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.