Melvern Lake
Osage County, Kansas6,930 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
↑ up from B at the last regrade
- Mesotrophic
- #2 of 5 in the county
- 88 ft max depth
- Public access
- Limited data
Melvern Lake in Osage County, Kansas has a water quality grade of A (Excellent). Water clarity: 4.8 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 6 µg/L. Surface area: 6930 acres.
- Clarity
- 4.8 ft
- Max depth
- ~88 ft est.
- Area
- 6,930 acres
- Type
- Mesotrophic
- Phosphorus
- 20 µg/L
- Chlorophyll-a
- 6 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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Watch Melvern Lake’s letter
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Melvern Lake is a 6,930-acre mesotrophic lake in Osage County, Kansas with an estimated average depth of about 88 feet. Water quality is graded A based on 2 sampling years through 2017. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 6 public boat landings. Compared to the 4 other monitored lakes in Osage County, Melvern Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2017-08-02. Grade methodology: LakeQuality methodology.
What Melvern Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch6 documented ramps
- Big water6,930 acres
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 A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Murky, only visible to about 4.8 ft. Phosphorus 20 µg/L. Chlorophyll-a 6 µg/L. TSI 50. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.8 ft | Not graded |
| Phosphorus | 20 µg/L | Good |
| Chlorophyll-a (Algae) | 6 µg/L | Good |
| Trophic State Index (TSI) | 50 | Mesotrophic |
Moderate nutrients, good water quality
Current Conditions
USGS snapshot Sep 7, 2026, 3:30 PM from gauge 06910997 (MELVERN LK NR MELVERN, KS). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.
→ Melvern Lake water level: the live USGS gauge reading
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~88 ft est. |
| Average Depth | ~61 ft est. |
| Surface Area | 6,930 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Kansas has not published bathymetry for Melvern 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.
Recreation & Access
- Melvern-WestPublic
- Melvern-EastPublic
- Turkey PointPublic
- Arrow RockPublic
- Melvern Lake Outlet ParkPublic
- Melvern Lake MarinaSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Melvern Lake
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.167 m/yr | 2 |
| Phosphorus | → Stable | +0.33 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +0.17 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Melvern Lake is a man-made reservoir impounded by the Melvern Dam (completed 1972), built primarily for flood risk reduction on the Marais Des Cygnes; earth-type dam, 123 ft tall and 9,750 ft long.
- Surface area
- 6,930 ac
- Normal storage
- 154,000 ac-ft
- Max storage
- 363,000 ac-ft
- Drainage area
- 349 sq mi
- Hazard class
- High
- Owner
- USACE - Kansas City District
All listed purposes: Flood Risk Reduction;Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID KS00007 · Operator website
County Ranking
Ranked #2 of 5 lakes in Osage County
Nearby Lakes in Osage County
Frequently asked questions about Melvern Lake
Where is Melvern Lake?
- Melvern Lake is a lake in Osage County, Kansas. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Melvern Lake?
- Melvern Lake in Osage County, Kansas has a water quality grade of A (Excellent). Water clarity: 4.8 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 6 µg/L. Surface area: 6930 acres.
Is Melvern Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Melvern Lake?
- No published bathymetric survey covers Melvern Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 88 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 6930 acres.
What is the water level at Melvern Lake?
- The USGS snapshot on this page for Melvern Lake is 1035.82 ft of water-surface elevation, recorded Sep 7, 2026, 3:30 PM at gauge 06910997. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.
Are there boat ramps on Melvern Lake?
- Melvern Lake has 6 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Melvern-West, Melvern-East, Turkey Point, Arrow Rock, among others. Public access is listed as yes.
Explore Melvern Lake across LakeQuality
More Kansas Lake Rankings
Other Grade A Lakes in Kansas
Mesotrophic Lakes in Kansas
Where this data comes from
11 measurements from 1 monitoring station, 2014–2017. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Kansas Department Of Health And Environment
21KAN001_WQX11 samples · 2014–2017
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory