Marion Co Lake
Marion County, Kansas150 acresView mapDirections
KDHE publishes the water-quality measurements for Marion Co Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 51 ft max depth
- Limited data
Marion Co Lake in Marion County, Kansas has water-quality measurements published by KDHE, shown here as reported. Water clarity: 2.9 ft visibility. Phosphorus: 82.5 µg/L. Chlorophyll-a (algae): 41.6 µg/L. Surface area: 150 acres.
Marion Co Lake is a 150-acre highly nutrient-loaded hypereutrophic lake in Marion County, Kansas with an estimated average depth of about 51 feet. Overall water quality is declining over recent sampling years. Compared to the 1 other monitored lakes in Marion County, Marion Co Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2018-07-31. Methodology: how these readings are compared.
Swimming conditions
Readings onlyRecreation use not supported
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. Marion Co Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
Whether Marion Co Lake is safe to swim in today is a call for the Kansas Department of Health and Environment and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Marion Co Lake
These are the measurements KDHE publishes for Marion Co Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 2.9 ft of visibility. Phosphorus 82.5 µg/L. Chlorophyll-a 41.6 µg/L. TSI 66.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 82.5µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 41.6µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 66 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Marion Co Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~51 ft est.
Surface area
150 acres
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Kansas has not published bathymetry for Marion Co Lake.
Lake Size & Watershed
Watershed (drainage) area
7 sq mi
HydroLAKES / HydroSHEDS
Shoreline
2.7 mi
HydroLAKES / HydroSHEDS
Elevation
1,345 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 Marion Co Lake
Compare lakeside cabins, hotels, and vacation rentals near Marion Co Lake in Marion County, Kansas — 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Marion Co Lake are listed below.
Top-rated places to stay near Marion Co Lake
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Fishing Marion Co Lake
Water quality readings over time
2 seasons of samples on record (2012–2018). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
Phosphorus
Improving-2.67 µg/L/yr2 years
Chlorophyll-a
Worsening+4.02 µg/L/yr2 years
Reservoir Info (USACE NID)
Marion Co Lake is a man-made reservoir impounded by the Marion County Lake Dam (completed 1937), built primarily for recreation on the Cottonwood River-Tr, 62 ft tall and 1,290 ft long.
- Surface area
- 150 ac
- Normal storage
- 2,418 ac-ft
- Max storage
- 4,063 ac-ft
- Drainage area
- 7.2 sq mi
- Hazard class
- Significant
- Owner
- MARION COUNTY
Source: USACE National Inventory of Dams, NID ID KS02548 · Operator website · Matched by proximity (0.16 km)
EPA Impairment Status
Marion Co Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Drinking water, Aquatic life, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit KS-LM012101 · Official waterbody report
Nearby Lakes in Marion County
Frequently asked questions about Marion Co Lake
Where is Marion Co Lake?
- Marion Co Lake is a lake in Marion County, Kansas. Its water-quality measurements are published by KDHE and shown on this page as reported.
What is the water quality of Marion Co Lake?
- Marion Co Lake in Marion County, Kansas has water-quality measurements published by KDHE, shown here as reported. Water clarity: 2.9 ft visibility. Phosphorus: 82.5 µg/L. Chlorophyll-a (algae): 41.6 µg/L. Surface area: 150 acres.
Is Marion Co Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Marion Co Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
How deep is Marion Co Lake?
- No published bathymetric survey covers Marion Co Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 51 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 150 acres.
Explore Marion Co Lake across LakeQuality
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Where this data comes from
8 measurements from 1 monitoring station, 2012–2018. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Kansas Department Of Health And Environment
21KAN001_WQX8 samples · 2012–2018
Analytical methods
- Depth, Secchi disk depth
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)