Sunnen Lake
Washington County, Missouri198 acresView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Impaired · Algal growth
- 72 ft max depth
- Limited data
Sunnen Lake in Washington County, Missouri is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1 ft visibility. Phosphorus: 61 µg/L. Chlorophyll-a (algae): 14.3 µg/L. Surface area: 198 acres.
- Clarity
- 1 ft
- Max depth
- ~72 ft est.
- Area
- 198 acres
Stays via Stay22
Stays near Sunnen Lake
Compare lakeside cabins, hotels, and vacation rentals near Sunnen Lake in Washington County, Missouri — 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.
Top-rated places to stay near Sunnen Lake
Prices for Sep 11–13, 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 whole trip? See where to stay at Missouri’s top lakes →
Watch Sunnen Lake’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
Why Sunnen Lake has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Sunnen Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by Missouri DNR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Sunnen Lake is a 198-acre lake in Washington County, Missouri with an estimated average depth of about 72 feet.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2023-08-16. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Sunnen Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
Water quality measurements for Sunnen Lake
These readings exist but are not enough for an A–F grade — see why.
Very murky, less than 1 ft of visibility. Phosphorus 61 µg/L. Chlorophyll-a 14.3 µg/L. TSI 66.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1 ft | Not graded |
| Phosphorus | 61 µg/L | Not graded |
| Chlorophyll-a (Algae) | 14.3 µg/L | Not graded |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~72 ft est. |
| Average Depth | ~23 ft est. |
| Surface Area | 198 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Missouri has not published bathymetry for Sunnen 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 Sunnen Lake
Reservoir Info (USACE NID)
Sunnen Lake is a man-made reservoir impounded by the Sunnen Dam (completed 1948), built primarily for recreation on the FOURCHE A RENAULT; earth-type dam, 51 ft tall and 1,300 ft long.
- Surface area
- 198 ac
- Normal storage
- 2,540 ac-ft
- Max storage
- 5,000 ac-ft
- Drainage area
- 26.85 sq mi
- Hazard class
- High
- Owner
- YMCA of the Ozarks
Source: USACE National Inventory of Dams, NID ID MO30111 · Operator website
EPA Impairment Status
Sunnen Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MO_7294.00 · Official waterbody report
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Sunnen Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Village Inn Trailer Court WwtpPotosi · 4.8 mi away · NPDES MO0123765Recent violation
- Ymca Of The Ozarks WwtfPotosi · 0.1 mi away · NPDES MO0127922
- Shirley SchoolPotosi · 2.6 mi away · NPDES MO0083810
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Graded lakes near Sunnen Lake
Sunnen Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Washington County
Frequently asked questions about Sunnen Lake
Where is Sunnen Lake?
- Sunnen Lake is a lake in Washington County, Missouri. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Sunnen Lake?
- Sunnen Lake in Washington County, Missouri is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1 ft visibility. Phosphorus: 61 µg/L. Chlorophyll-a (algae): 14.3 µg/L. Surface area: 198 acres.
Is Sunnen Lake safe to swim in?
- The letter is not a swimming clearance. Sunnen Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
How deep is Sunnen Lake?
- No published bathymetric survey covers Sunnen Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 72 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 198 acres.
Explore Sunnen Lake across LakeQuality
More Missouri Lake Rankings
Other Lakes in Missouri
Eutrophic Lakes in Missouri
Where this data comes from
3 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Missouri Dept. of Natural Resources
MDNR3 samples · 2023
Analytical methods
- Depth, Secchi disk in meters
- Nitrogen and Phosphorus, Total, Whole-water, Alkaline Persulfate Digest
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)