Gardner Lake
Johnson County, Kansas130 acresView mapDirections
Nutrients and algae run well above the regional average.
↓ down from C at the last regrade
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #5 of 13 in the county
- 42 ft max depth
- Limited data
Gardner Lake in Johnson County, Kansas has a water quality grade of F (Algae-prone). Water clarity: 2.3 ft visibility. Phosphorus: 37 µg/L. Chlorophyll-a (algae): 43.5 µg/L. Surface area: 130 acres.
- Clarity
- 2.3 ft
- Max depth
- ~42 ft est.
- Area
- 130 acres
- Type
- Hypereutrophic
- Phosphorus
- 37 µg/L
- Chlorophyll-a
- 43.5 µg/L
- Trend
- ↓ Declining
Stays via Stay22
Stays near Gardner Lake
Compare lakeside cabins, hotels, and vacation rentals near Gardner Lake in Johnson 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 Gardner Lake are listed below.
Top-rated places to stay near Gardner Lake
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Watch Gardner Lake’s letter
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Gardner Lake is a 130-acre highly nutrient-loaded hypereutrophic lake in Johnson County, Kansas with an estimated average depth of about 42 feet. Water quality is graded F based on 1 sampling years through 2018. Overall water quality is declining over recent sampling years. Compared to the 12 other monitored lakes in Johnson County, Gardner Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2018-08-06. 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 F is nutrients and algae, not a swimming clearance. Gardner Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 2.3 ft of visibility. Phosphorus 37 µg/L. Chlorophyll-a 43.5 µg/L. TSI 63. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.3 ft | Not graded |
| Phosphorus | 37 µg/L | Not graded |
| Chlorophyll-a (Algae) | 43.5 µg/L | Poor |
| Trophic State Index (TSI) | 63 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~42 ft est. |
| Average Depth | ~11 ft est. |
| Surface Area | 130 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 Gardner 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 Gardner Lake
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.025 m/yr | 2 |
| Phosphorus | ↓ Declining | +3.17 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +1.83 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Gardner Lake is a man-made reservoir impounded by the Gardner Lake Dam (completed 1940), built primarily for water supply on the Kill Creek; other-type dam, 61 ft tall and 1,550 ft long.
- Surface area
- 130 ac
- Normal storage
- 2,060 ac-ft
- Max storage
- 3,618 ac-ft
- Drainage area
- 5.34 sq mi
- Hazard class
- High
- Owner
- GARDNER, CITY OF
All listed purposes: Water Supply;Recreation.
Source: USACE National Inventory of Dams, NID ID KS02488 · Operator website
EPA Impairment Status
Gardner 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-LM040401 · Official waterbody report · Matched by proximity (1 km)
County Ranking
Ranked #5 of 13 lakes in Johnson County
Nearby Lakes With Higher Grades
Gardner Lake holds Grade F. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Johnson County
Frequently asked questions about Gardner Lake
Where is Gardner Lake?
- Gardner Lake is a lake in Johnson County, Kansas. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Gardner Lake?
- Gardner Lake in Johnson County, Kansas has a water quality grade of F (Algae-prone). Water clarity: 2.3 ft visibility. Phosphorus: 37 µg/L. Chlorophyll-a (algae): 43.5 µg/L. Surface area: 130 acres.
Is Gardner Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Gardner Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
How deep is Gardner Lake?
- No published bathymetric survey covers Gardner Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 42 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 130 acres.
Explore Gardner Lake across LakeQuality
More Kansas Lake Rankings
Other Grade F Lakes in Kansas
Hypereutrophic Lakes in Kansas
Where this data comes from
8 measurements from 1 monitoring station, 2012–2018. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Kansas Department Of Health And Environment
21KAN001_WQX8 samples · 2012–2018
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)