Lake Marie
Mercer County, Missouri30 acresView mapDirections
Missouri DNR publishes the water-quality measurements for Lake Marie. Here is what has been measured.
- Mesotrophic
- 34 ft max depth
Lake Marie in Mercer County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 7.8 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 2.7 µg/L. Surface area: 30 acres.
Lake Marie is a 30-acre mesotrophic lake in Mercer County, Missouri with an estimated average depth of about 34 feet. Overall water quality is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2023-08-01. Methodology: how these readings are compared.
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. Check local advisories before you swim.
Whether Lake Marie 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 Marie
These are the measurements Missouri DNR publishes for Lake Marie, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 7.8 ft. Phosphorus 13 µg/L. Chlorophyll-a 2.7 µg/L. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 7.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 13µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2.7µg/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. | 43 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Lake Marie
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Lake Marie typically sits around 83°F at the surface in August. Summer average is about 81°F. Usually warmest in Jul (about 83°F) and coldest in May (about 70°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (70°F) to its warmest (83°F).
Typical surface water temperature by month, from 12 field readings (2021–2023) via the EPA Water Quality Portal. See the full Lake Marie water temperature breakdown →
Lake Details
Max depth
~34 ft est.
Surface area
30 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 Marie.
Lake Size & Watershed
Watershed (drainage) area
2 sq mi
HydroLAKES / HydroSHEDS
Shoreline
1.2 mi
HydroLAKES / HydroSHEDS
Elevation
968 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 Marie
Compare lakeside cabins, hotels, and vacation rentals near Lake Marie in Mercer 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 Marie
Prices for Oct 23–25, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Missouri’s top lakes →
Follow Lake Marie’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Lake Marie
Water quality readings over time
3 seasons of samples on record (2021–2023). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving3 years
Phosphorus
Improving-2.05 µg/L/yr3 years
Chlorophyll-a
Improving-1.1 µg/L/yr3 years
Reservoir Info (USACE NID)
Lake Marie is a man-made reservoir impounded by the Lake Marie Dam (completed 1981), built primarily for recreation on the POPS BRANCH; earth-type dam, 50 ft tall and 1,100 ft long.
- Surface area
- 30 ac
- Normal storage
- 882 ac-ft
- Max storage
- 970 ac-ft
- Drainage area
- 0.53 sq mi
- Hazard class
- High
- Owner
- LAKE MARIE HOA
Source: USACE National Inventory of Dams, NID ID MO10154 · Operator website
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Lake Marie under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Twin Lakes WwtfMercer · 0.2 mi away · NPDES MO0129216Recent violation
- Mercer WwtfMercer · 2.2 mi away · NPDES MO0056057Recent 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 Mercer County
Frequently asked questions about Lake Marie
Where is Lake Marie?
- Lake Marie is a lake in Mercer 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 Marie?
- Lake Marie in Mercer County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 7.8 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 2.7 µg/L. Surface area: 30 acres.
Is Lake Marie safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Lake Marie?
- Lake Marie typically sits around 83°F at the surface in August, from 12 EPA Water Quality Portal field readings (2021–2023). That is a typical value for the month, not a live reading.
How deep is Lake Marie?
- No published bathymetric survey covers Lake Marie, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 34 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 30 acres.
Explore Lake Marie across LakeQuality
More lakes in Missouri
Other Lakes in Missouri
Mesotrophic Lakes in Missouri
Where this data comes from
60 measurements from 1 monitoring station, 2021–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC60 samples · 2021–2023
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)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)