Garnett Lake
Anderson County, Kansas45 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 · Nutrients (phosphorus, nitrogen)
- 22 ft max depth
- Limited data
Garnett Lake in Anderson County, Kansas is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 2.4 ft visibility. Phosphorus: 69.5 µg/L. Chlorophyll-a (algae): 160 µg/L. Surface area: 45 acres.
- Clarity
- 2.4 ft
- Max depth
- ~22 ft est.
- Area
- 45 acres
- Phosphorus
- 69.5 µg/L
- Chlorophyll-a
- 160 µg/L
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Watch Garnett Lake’s letter
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Why Garnett 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 Garnett 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 KDHE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Garnett Lake is a 45-acre lake in Anderson County, Kansas with an estimated average depth of about 22 feet.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2017-08-14. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Garnett Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water quality measurements for Garnett Lake
These readings exist but are not enough for an A–F grade — see why.
Very murky, less than 2.4 ft of visibility. Phosphorus 69.5 µg/L. Chlorophyll-a 160 µg/L. TSI 70.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.4 ft | Not graded |
| Phosphorus | 69.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 160 µg/L | Not graded |
| Trophic State Index (TSI) | 70 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~22 ft est. |
| Average Depth | ~9 ft est. |
| Surface Area | 45 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 Garnett 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 Garnett Lake
Reservoir Info (USACE NID)
Garnett Lake is a man-made reservoir impounded by the Garnett City Dam (completed 1935), built primarily for recreation on the Pottawatomie Creek-Tr; earth-type dam, 60 ft tall and 1,100 ft long.
- Surface area
- 45 ac
- Normal storage
- 840 ac-ft
- Max storage
- 920 ac-ft
- Drainage area
- 2.11 sq mi
- Hazard class
- Low
- Owner
- GARNETT, CITY OF
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID KS00202 · Operator website
EPA Impairment Status
Garnett Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit KS-LM040601 · Official waterbody report · Matched by proximity (0.6 km)
Graded lakes near Garnett Lake
Garnett Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Anderson County
Frequently asked questions about Garnett Lake
Where is Garnett Lake?
- Garnett Lake is a lake in Anderson County, Kansas. 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 Garnett Lake?
- Garnett Lake in Anderson County, Kansas is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 2.4 ft visibility. Phosphorus: 69.5 µg/L. Chlorophyll-a (algae): 160 µg/L. Surface area: 45 acres.
Is Garnett Lake safe to swim in?
- The letter is not a swimming clearance. Garnett Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Garnett Lake?
- No published bathymetric survey covers Garnett Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 22 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 45 acres.
Explore Garnett Lake across LakeQuality
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Where this data comes from
5 measurements from 1 monitoring station, 2017. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Kansas Department Of Health And Environment
21KAN001_WQX5 samples · 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)