El Dorado Lake
Butler County, Kansas8,400 acresView mapDirections
Nutrients and algae sit mid-range for this region.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #1 of 3 in the county
- 80 ft max depth
- Public access
- Limited data
El Dorado Lake in Butler County, Kansas has a water quality grade of C (Fair). Water clarity: 2.8 ft visibility. Phosphorus: 34 µg/L. Chlorophyll-a (algae): 14.3 µg/L. Surface area: 8400 acres.
- Clarity
- 2.8 ft
- Max depth
- ~80 ft est.
- Area
- 8,400 acres
- Type
- Eutrophic
- Phosphorus
- 34 µg/L
- Chlorophyll-a
- 14.3 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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El Dorado Lake is a 8,400-acre productive, nutrient-rich eutrophic lake in Butler County, Kansas with an estimated average depth of about 80 feet. Water quality is graded C 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 9 public boat landings. Compared to the 2 other monitored lakes in Butler County, El Dorado Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2017-07-17. Grade methodology: LakeQuality methodology.
What El Dorado Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch9 documented ramps
- Big water8,400 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 C is nutrients and algae, not a swimming clearance. El Dorado Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), sediment / turbidity. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Very murky, less than 2.8 ft of visibility. Phosphorus 34 µg/L. Chlorophyll-a 14.3 µg/L. TSI 58. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.8 ft | Not graded |
| Phosphorus | 34 µg/L | Good |
| Chlorophyll-a (Algae) | 14.3 µg/L | Fair |
| Trophic State Index (TSI) | 58 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~80 ft est. |
| Average Depth | ~33 ft est. |
| Surface Area | 8,400 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 El Dorado 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
- El Dorado-Walnut RiverPublic
- El Dorado-NE 60th StreetPublic
- El Dorado-NE Cole CreekPublic
- El Dorado-Area 1Public
- El Dorado-Goose CovePublic
- El Dorado-Quail RunPublic
Showing 6 of 9 documented landings from the USGS National Boat Ramps inventory.
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing El Dorado Lake
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.107 m/yr | 2 |
| Phosphorus | ↓ Declining | +4.5 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +4.13 µg/L/yr | 2 |
Reservoir Info (USACE NID)
El Dorado Lake is a man-made reservoir impounded by the El Dorado Dam (completed 1981), built primarily for flood risk reduction on the Walnut River; earth-type dam, 99 ft tall and 20,930 ft long.
- Surface area
- 8,400 ac
- Normal storage
- 161,928 ac-ft
- Max storage
- 246,882 ac-ft
- Drainage area
- 234 sq mi
- Hazard class
- High
- Owner
- USACE - Tulsa District
All listed purposes: Flood Risk Reduction;Other;Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID KS00027 · Operator website
EPA Impairment Status
El Dorado 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-LM033001 · Official waterbody report
County Ranking
Ranked #1 of 3 lakes in Butler County
Nearby Lakes in Butler County
Frequently asked questions about El Dorado Lake
Where is El Dorado Lake?
- El Dorado Lake is a lake in Butler County, Kansas. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for El Dorado Lake?
- El Dorado Lake in Butler County, Kansas has a water quality grade of C (Fair). Water clarity: 2.8 ft visibility. Phosphorus: 34 µg/L. Chlorophyll-a (algae): 14.3 µg/L. Surface area: 8400 acres.
Is El Dorado Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. El Dorado Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), sediment / turbidity. Check local advisories before you swim.
How deep is El Dorado Lake?
- No published bathymetric survey covers El Dorado Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 80 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 8400 acres.
Are there boat ramps on El Dorado Lake?
- El Dorado Lake has 9 documented boat landings in the USGS National Boat Ramps inventory. Named access points include El Dorado-Walnut River, El Dorado-NE 60th Street, El Dorado-NE Cole Creek, El Dorado-Area 1, among others. Public access is listed as yes.
Explore El Dorado Lake across LakeQuality
More Kansas Lake Rankings
Other Grade C Lakes in Kansas
Eutrophic 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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory