Strowbridge Reservoir
Osage County, Kansas239 acresView mapDirections
Nutrients and algae run above the regional average.
↓ down from C at the last regrade
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #4 of 5 in the county
- 31 ft max depth
- Limited data
Strowbridge Reservoir in Osage County, Kansas has a water quality grade of D (Nutrient-rich). Water clarity: 2.4 ft visibility. Phosphorus: 48.5 µg/L. Chlorophyll-a (algae): 27 µg/L. Surface area: 239 acres.
- Clarity
- 2.4 ft
- Max depth
- ~31 ft est.
- Area
- 239 acres
- Type
- Eutrophic
- Phosphorus
- 48.5 µg/L
- Chlorophyll-a
- 27 µg/L
- Trend
- ↓ Declining
Stays via Stay22
Stays near Strowbridge Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Strowbridge Reservoir in Osage 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 Strowbridge Reservoir are listed below.
Top-rated places to stay near Strowbridge Reservoir
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 Kansas’s top lakes →
Watch Strowbridge Reservoir’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
Strowbridge Reservoir is a 239-acre productive, nutrient-rich eutrophic lake in Osage County, Kansas with an estimated average depth of about 31 feet. Water quality is graded D based on 1 sampling years through 2018. Overall water quality is declining over recent sampling years. Compared to the 4 other monitored lakes in Osage County, Strowbridge Reservoir ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2018-06-18. 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 D is nutrients and algae, not a swimming clearance. Strowbridge Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 2.4 ft of visibility. Phosphorus 48.5 µg/L. Chlorophyll-a 27 µg/L. TSI 63. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.4 ft | Not graded |
| Phosphorus | 48.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 27 µg/L | Poor |
| Trophic State Index (TSI) | 63 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~31 ft est. |
| Average Depth | ~10 ft est. |
| Surface Area | 239 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 Strowbridge Reservoir.
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 Strowbridge Reservoir
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.057 m/yr | 2 |
| Phosphorus | ↑ Improving | -6.67 µg/L/yr | 2 |
| Chlorophyll-a | ↓ Declining | +0.6 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Strowbridge Reservoir is a man-made reservoir impounded by the Strowbridge Dam (completed 1966), built primarily for recreation on the Strowbridge Creek; earth-type dam, 45 ft tall and 1,435 ft long.
- Surface area
- 239 ac
- Normal storage
- 3,100 ac-ft
- Max storage
- 4,900 ac-ft
- Drainage area
- 5 sq mi
- Hazard class
- High
- Owner
- CARBONDALE, CITY OF
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID KS02518 · Operator website
EPA Impairment Status
Strowbridge Reservoir 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-LM051201 · Official waterbody report
County Ranking
Ranked #4 of 5 lakes in Osage County
Nearby Lakes in Osage County
Frequently asked questions about Strowbridge Reservoir
Where is Strowbridge Reservoir?
- Strowbridge Reservoir is a lake in Osage County, Kansas. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Strowbridge Reservoir?
- Strowbridge Reservoir in Osage County, Kansas has a water quality grade of D (Nutrient-rich). Water clarity: 2.4 ft visibility. Phosphorus: 48.5 µg/L. Chlorophyll-a (algae): 27 µg/L. Surface area: 239 acres.
Is Strowbridge Reservoir safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Strowbridge Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Strowbridge Reservoir?
- No published bathymetric survey covers Strowbridge Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 31 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 239 acres.
Explore Strowbridge Reservoir across LakeQuality
More Kansas Lake Rankings
Other Grade D Lakes in Kansas
Eutrophic Lakes in Kansas
Where this data comes from
8 measurements from 1 monitoring station, 2015–2018. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Kansas Department Of Health And Environment
21KAN001_WQX8 samples · 2015–2018
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)