Foss Reservoir
Custer County, Oklahoma13,141 acresView mapDirections
Oklahoma DEQ publishes the water-quality measurements for Foss Reservoir. Here is what has been measured.
- 76 ft max depth
- Public access
- Limited data
Foss Reservoir in Custer County, Oklahoma has water-quality measurements published by Oklahoma DEQ, shown here as reported. Water clarity: 3.9 ft visibility. Surface area: 13141 acres.
Foss Reservoir is a 13,141-acre lake in Custer County, Oklahoma with an estimated average depth of about 76 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 5 public boat landings.
Source: EPA Water Quality Portal sampling records, ODEQ, last sampled 2024-10-07. Methodology: how these readings are compared.
What Foss Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch5 documented ramps
- Big water13,141 acres
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Foss Reservoir is safe to swim in today is a call for the Oklahoma Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Foss Reservoir
These are the measurements Oklahoma DEQ publishes for Foss Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.9 ft. TSI 57.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 57 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Foss Reservoir
Answers come straight from the public measurements and survey records on this page.
→ Foss Reservoir water level: the live USGS gauge reading
Lake Details
Max depth
~76 ft est.
Surface area
13,141 acres
Public access
Yes
Listed by Oklahoma DEQ
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Oklahoma has not published bathymetry for Foss Reservoir.
Lake Size & Watershed
Watershed (drainage) area
1,454 sq mi
HydroLAKES / HydroSHEDS
Shoreline
27.8 mi
HydroLAKES / HydroSHEDS
Elevation
1,663 ft
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
- Copper CovePublic
- Sandy Beach RoadPublic
- Mouse CreekPublic
- NorthsidePublic
- CutberthPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Foss Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Foss Reservoir in Custer County, Oklahoma — 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 Foss Reservoir
Prices for Nov 6–8, 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 trip? Cabins and lodging at Foss Reservoir → · more Oklahoma lake trips
Follow Foss Reservoir’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Foss Reservoir
Water quality readings over time
2 seasons of samples on record (2016–2018). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
Reservoir Info (USACE NID)
Foss Reservoir is a man-made reservoir impounded by the Foss Dam (completed 1961), built primarily for flood risk reduction on the Washita River; earth-type dam, 142 ft tall and 18,130 ft long.
- Surface area
- 13,141 ac
- Normal storage
- 168,732 ac-ft
- Max storage
- 816,900 ac-ft
- Drainage area
- 1,473 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
Source: USACE National Inventory of Dams, NID ID OK02503 · Operator website
Nearby Lakes in Custer County
Frequently asked questions about Foss Reservoir
Where is Foss Reservoir?
- Foss Reservoir is a lake in Custer County, Oklahoma. Its water-quality measurements are published by Oklahoma DEQ and shown on this page as reported.
What is the water quality of Foss Reservoir?
- Foss Reservoir in Custer County, Oklahoma has water-quality measurements published by Oklahoma DEQ, shown here as reported. Water clarity: 3.9 ft visibility. Surface area: 13141 acres.
Is Foss Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Foss Reservoir?
- No published bathymetric survey covers Foss Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 76 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 13141 acres.
Are there boat ramps on Foss Reservoir?
- Foss Reservoir has 5 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Copper Cove, Sandy Beach Road, Mouse Creek, Northside, among others. Public access is listed as yes.
Can I fish at Foss Reservoir?
- Foss Reservoir has 5 documented boat landings in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Oklahoma's fish and wildlife agency, so check its current regulations before you go.
Explore Foss Reservoir across LakeQuality
More lakes in Oklahoma
Other Lakes in Oklahoma
Eutrophic Lakes in Oklahoma
Where this data comes from
68 measurements from 5 monitoring stations, 2016–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- OWRB Lakes Monitoring
OKWRB-LAKES_WQX68 samples · 2016–2024
Analytical methods
- OWRB Lakes Field Data Collection
- Determination of Turbidity
Monitoring station identifiers (5)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory