Marion Lake
Marion County, Kansas6,210 acresView mapDirections
KDHE publishes the water-quality measurements for Marion Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 78 ft max depth
- Public access
Marion Lake in Marion County, Kansas has water-quality measurements published by KDHE, shown here as reported. Water clarity: 2 ft visibility. Phosphorus: 230 µg/L. Chlorophyll-a (algae): 36.3 µg/L. Surface area: 6210 acres.
Marion Lake is a 6,210-acre highly nutrient-loaded hypereutrophic lake in Marion County, Kansas with an estimated average depth of about 78 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 3 public boat landings. Compared to the 1 other monitored lakes in Marion County, Marion Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2022-08-04. Methodology: how these readings are compared.
What Marion Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch3 documented ramps
- Camping3 public campgrounds nearby
- Big water6,210 acres
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 Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Marion 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 Lake
These are the measurements KDHE publishes for Marion 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 ft of visibility. Phosphorus 230 µg/L. Chlorophyll-a 36.3 µg/L. TSI 72.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 230µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 36.3µg/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. | 72 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Marion Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~78 ft est.
Surface area
6,210 acres
Public access
Yes
Listed by KDHE
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 Lake.
Lake Size & Watershed
Watershed (drainage) area
204 sq mi
HydroLAKES / HydroSHEDS
Shoreline
26.5 mi
HydroLAKES / HydroSHEDS
Elevation
1,352 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.
Recreation & Access
- Marion-French CreekPublic
- Marion-Cotton WoodPublic
- Marion-HillsboroPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Marion Lake
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Stays via Stay22
Stays near Marion Lake
Compare lakeside cabins, hotels, and vacation rentals near Marion 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 Lake are listed below.
Top-rated places to stay near Marion Lake
Prices for Oct 30–Nov 1, 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 trip? Cabins and lodging at Marion Lake → · more Kansas lake trips
Follow Marion Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Marion Lake
Water quality readings over time
3 seasons of samples on record (2014–2022). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving3 years
Phosphorus
Improving-15 µg/L/yr2 years
Chlorophyll-a
Improving-3.04 µg/L/yr3 years
Reservoir Info (USACE NID)
Marion Lake is a man-made reservoir impounded by the Marion Dam (completed 1968), built primarily for flood risk reduction on the Cottonwood River; gravity-type dam, 67 ft tall and 8,375 ft long.
- Surface area
- 6,210 ac
- Normal storage
- 80,680 ac-ft
- Max storage
- 189,200 ac-ft
- Drainage area
- 200 sq mi
- Hazard class
- High
- Owner
- USACE - Tulsa District
All listed purposes: Flood Risk Reduction;Other;Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID KS00006 · Operator website
EPA Impairment Status
Marion 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-LM020001 · Official waterbody report
Nearby Lakes in Marion County
Frequently asked questions about Marion Lake
Where is Marion Lake?
- Marion 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 Lake?
- Marion Lake in Marion County, Kansas has water-quality measurements published by KDHE, shown here as reported. Water clarity: 2 ft visibility. Phosphorus: 230 µg/L. Chlorophyll-a (algae): 36.3 µg/L. Surface area: 6210 acres.
Is Marion Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Marion Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Marion Lake?
- No published bathymetric survey covers Marion Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 78 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 6210 acres.
Are there boat ramps on Marion Lake?
- Marion Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Marion-French Creek, Marion-Cotton Wood, Marion-Hillsboro. Public access is listed as yes.
Can I fish at Marion Lake?
- Marion Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Kansas's fish and wildlife agency, so check its current regulations before you go.
Are there campgrounds on Marion Lake?
- Marion Lake has 3 public campgrounds from USGS The National Map within 5 km, including Cottonwood Point, Hillsboro Cove, French Creek. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Marion Lake across LakeQuality
More lakes in Kansas
Other Lakes in Kansas
Hypereutrophic Lakes in Kansas
Where this data comes from
26 measurements from 6 monitoring stations, 2014–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Kansas Water Science Center
USGS-KS15 samples · 2022 - Kansas Department Of Health And Environment
21KAN001_WQX11 samples · 2014–2017
Analytical methods
- Plant pigments, sonication & 445
- YSI EXO turbidity sensor, FNU
- Depth, Secchi disk depth
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (6)
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)
Named boat-access points from the USGS National Boat Ramps inventory
Public campgrounds from USGS The National Map Structures, within about 3 miles