Mound City Lake
Linn County, Kansas148 acresView mapDirections
Nutrients and algae run above the regional average.
↓ down from C at the last regrade
- Eutrophic
- Impaired · Noxious aquatic plants
- #2 of 2 in the county
- Limited data
Mound City Lake in Linn County, Kansas has a water quality grade of D (Nutrient-rich). Water clarity: 3.6 ft visibility. Phosphorus: 50 µg/L. Chlorophyll-a (algae): 24 µg/L. Surface area: 148 acres.
- Clarity
- 3.6 ft
- Area
- 148 acres
- Type
- Eutrophic
- Phosphorus
- 50 µg/L
- Chlorophyll-a
- 24 µg/L
- Trend
- ↑ Improving
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Stays near Mound City Lake
Compare lakeside cabins, hotels, and vacation rentals near Mound City Lake in Linn 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 grade measures nutrients and algae, not lodging — cabins and rentals around Mound City Lake are listed below.
Top-rated places to stay near Mound City Lake
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Watch Mound City Lake’s letter
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Mound City Lake is a 148-acre productive, nutrient-rich eutrophic lake in Linn County, Kansas. Water quality is graded D based on 2 sampling years through 2017. Overall water quality is improving over recent sampling years. Compared to the 1 other monitored lakes in Linn County, Mound City Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2017-08-14. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited 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 D is nutrients and algae, not a swimming clearance. Mound City Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for noxious aquatic plants, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 3.6 ft. Phosphorus 50 µg/L. Chlorophyll-a 24 µg/L. TSI 60. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.6 ft | Not graded |
| Phosphorus | 50 µg/L | Fair |
| Chlorophyll-a (Algae) | 24 µg/L | Poor |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 148 acres |
No bathymetric survey has been published for Mound City Lake, so its depth is not documented here.
Fishing Mound City Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.04 m/yr | 2 |
| Phosphorus | ↑ Improving | -5.8 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +1.54 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Mound City Lake is a man-made reservoir impounded by the Water Supply Lake, built primarily for water supply; earth-type dam, 32 ft tall and 1,450 ft long.
- Surface area
- 148 ac
- Normal storage
- 1,773 ac-ft
- Max storage
- 3,462 ac-ft
- Drainage area
- 5.74 sq mi
- Hazard class
- Significant
- Owner
- MOUND CITY, CITY OF
Source: USACE National Inventory of Dams, NID ID KS07334 · Operator website · Matched by proximity (0.1 km)
EPA Impairment Status
Mound City Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit KS-LM051401 · Official waterbody report
County Ranking
Ranked #2 of 2 lakes in Linn County
Nearby Lakes in Linn County
Frequently asked questions about Mound City Lake
Where is Mound City Lake?
- Mound City Lake is a lake in Linn County, Kansas. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Mound City Lake?
- Mound City Lake in Linn County, Kansas has a water quality grade of D (Nutrient-rich). Water clarity: 3.6 ft visibility. Phosphorus: 50 µg/L. Chlorophyll-a (algae): 24 µg/L. Surface area: 148 acres.
Is Mound City Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Mound City Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for noxious aquatic plants, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
Explore Mound City Lake across LakeQuality
More Kansas Lake Rankings
Other Grade D Lakes in Kansas
Eutrophic Lakes in Kansas
Where this data comes from
10 measurements from 1 monitoring station, 2012–2017. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Kansas Department Of Health And Environment
21KAN001_WQX10 samples · 2012–2017
Analytical methods
- Depth, Secchi disk depth
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (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.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database