Mission Lake
Brown County, Kansas154 acresView mapDirections
Nutrients and algae sit mid-range for this region.
↑ up from D at the last regrade
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #1 of 2 in the county
- 41 ft max depth
- Limited data
Mission Lake in Brown County, Kansas has a water quality grade of C (Fair). Water clarity: 1 ft visibility. Phosphorus: 170 µg/L. Chlorophyll-a (algae): 9.3 µg/L. Surface area: 154 acres.
- Clarity
- 1 ft
- Max depth
- ~41 ft est.
- Area
- 154 acres
- Type
- Eutrophic
- Phosphorus
- 170 µg/L
- Chlorophyll-a
- 9.3 µg/L
- Trend
- → Stable
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Watch Mission Lake’s letter
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Mission Lake is a 154-acre productive, nutrient-rich eutrophic lake in Brown County, Kansas with an estimated average depth of about 41 feet. Water quality is graded C based on 2 sampling years through 2017. Phosphorus level is improving over recent sampling years. Compared to the 1 other monitored lakes in Brown County, Mission Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2017-09-12. 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 C is nutrients and algae, not a swimming clearance. Mission Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), pesticides, sediment / turbidity. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Very murky, less than 1 ft of visibility. Phosphorus 170 µg/L. Chlorophyll-a 9.3 µg/L. TSI 69. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1 ft | Not graded |
| Phosphorus | 170 µg/L | Poor |
| Chlorophyll-a (Algae) | 9.3 µg/L | Good |
| Trophic State Index (TSI) | 69 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~41 ft est. |
| Average Depth | ~13 ft est. |
| Surface Area | 154 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 Mission Lake.
Lake Size & Watershed
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.
Fishing Mission Lake
Water Quality Trend: → Stable
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.002 m/yr | 2 |
| Phosphorus | ↑ Improving | -10 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +19.72 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Mission Lake is a man-made reservoir impounded by the Mission Lake (completed 1924), built primarily for water supply on the Mission Creek; earth-type dam, 36 ft tall and 1,010 ft long.
- Surface area
- 154 ac
- Normal storage
- 1,070 ac-ft
- Max storage
- 2,450 ac-ft
- Drainage area
- 8.52 sq mi
- Hazard class
- High
- Owner
- HORTON, CITY OF
All listed purposes: Water Supply;Recreation.
Source: USACE National Inventory of Dams, NID ID KS02458 · Operator website
EPA Impairment Status
Mission 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-LM013601 · Official waterbody report
County Ranking
Ranked #1 of 2 lakes in Brown County
Nearby Lakes in Brown County
Frequently asked questions about Mission Lake
Where is Mission Lake?
- Mission Lake is a lake in Brown County, Kansas. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Mission Lake?
- Mission Lake in Brown County, Kansas has a water quality grade of C (Fair). Water clarity: 1 ft visibility. Phosphorus: 170 µg/L. Chlorophyll-a (algae): 9.3 µg/L. Surface area: 154 acres.
Is Mission Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Mission Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), pesticides, sediment / turbidity. Check local advisories before you swim.
How deep is Mission Lake?
- No published bathymetric survey covers Mission Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 41 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 154 acres.
Explore Mission Lake across LakeQuality
More Kansas Lake Rankings
Other Grade C Lakes in Kansas
Eutrophic Lakes in Kansas
Where this data comes from
10 measurements from 1 monitoring station, 2013–2017. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Kansas Department Of Health And Environment
21KAN001_WQX10 samples · 2013–2017
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
Lake size & watershed from HydroLAKES (HydroSHEDS)