Lake Marseilles-Terre du Lac Lakes is a 56-acre cold, clear oligotrophic lake in St. Francois County, Missouri. Water quality is graded A based on 3 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: 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 14.1 ft. Phosphorus level: 7.4 µg/L. Chlorophyll-a: 2.4 µg/L. Trophic State Index: 37.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 14.1 ft | B |
| Phosphorus | 7.4 µg/L | A |
| Chlorophyll-a (Algae) | 2.4 µg/L | A |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 56 acres |
Where to stay near Lake Marseilles-Terre du Lac Lakes
Compare lakeside cabins, hotels, and vacation rentals near Lake Marseilles-Terre du Lac Lakes 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.
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Fishing Lake Marseilles-Terre du Lac Lakes
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 | +0.46 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.28 µg/L/yr | 5 |
Water Temperature
Lake Marseilles-Terre du Lac Lakes averages about 81°F at the surface in summer, usually warmest in Jul (about 83°F) and coldest in Jun (about 79°F). These are typical values by month — not a live reading.
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 →
Location
County Ranking
Ranked #2 of 4 lakes in St. Francois County
Nearby Lakes in St. Francois County
Explore Lake Marseilles-Terre du Lac Lakes across LakeGrade
Species activity outlook by water temperature and season
Where to stay at Missouri's top lakes, each with its grade
Low nutrients, clear water, excellent for swimming
Missouri's cleanest and most-polluted lakes, ranked
More Missouri Lake Rankings
Other Grade A Lakes in Missouri
Washington County · Clarity: 11.1 ft
Ste. Genevieve County · Clarity: 9.9 ft
Iron County · Clarity: 13.1 ft
Jefferson County · Clarity: 12.9 ft
Perry County · Clarity: 12 ft
Warren County · Clarity: 12.6 ft
Oligotrophic Lakes in Missouri
More records, surveys & data sources
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
Source: EPA ATTAINS assessment unit MO_7614.00 · Official waterbody report · Matched by proximity (0.31 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
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 WwtpBonne Terre · 0.6 mi away · NPDES MO0095311Recent violation
- West St. Francois R-Iv Schools WwtpPark Hills · 2.1 mi away · NPDES MO0125083Recent violation
- Leadwood WwtpLeadwood · 3 mi away · NPDES MO0104256Recent violation
- St. Francois County Environmental CorpPark Hills · 4.5 mi away · NPDES MO0108774
- ImperialBonne 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.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2020-08-31
Monitoring stations: 1