O'Neill Forebay
Merced County, California2,246 acresView mapDirections
No nutrient or algae sampling on record from SWRCB for this lake.
- Impaired · Mercury
- Public access
- Limited data
O'Neill Forebay in Merced County, California has water-quality measurements published by SWRCB, shown here as reported. Surface area: 2246 acres.
O'Neill Forebay is a 2,246-acre lake in Merced County, California. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, your state environmental agency. Methodology: how these readings are compared.
What O'Neill Forebay is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Camping3 public campgrounds nearby
- Big water2,246 acres
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. O'Neill Forebay is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pCBs. Check local advisories before you swim.
Whether O'Neill Forebay is safe to swim in today is a call for the California State Water Resources Control Board and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for O'Neill Forebay
These are the measurements SWRCB publishes for O'Neill Forebay, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data.
Ask about O'Neill Forebay
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
2,246 acres
Shoreline
14.2 mi
Public access
Yes
Listed by SWRCB
No bathymetric survey has been published for O'Neill Forebay, so its depth is not documented here.
Recreation & Access
- San Luis Reservoir State Recreation AreaPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near O'Neill Forebay
- San Luis Creek Group Camp0.9 km
- Medeiros Campground2.5 km
- San Luis Creek Campground2.6 km
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Stays via Stay22
Stays near O'Neill Forebay
Compare lakeside cabins, hotels, and vacation rentals near O'Neill Forebay in Merced County, California — 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 O'Neill Forebay
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Fishing O'Neill Forebay
EPA Impairment Status
O'Neill Forebay is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption.
Source: EPA ATTAINS assessment unit CAL5423103220000209134612 · Official waterbody report
Nearby Lakes in Merced County
Frequently asked questions about O'Neill Forebay
Where is O'Neill Forebay?
- O'Neill Forebay is a lake in Merced County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.
What is the water quality of O'Neill Forebay?
- O'Neill Forebay in Merced County, California has water-quality measurements published by SWRCB, shown here as reported. Surface area: 2246 acres.
Is O'Neill Forebay safe to swim in?
- Nutrient and algae readings are not a swimming clearance. O'Neill Forebay is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pCBs. Check local advisories before you swim.
Are there boat ramps on O'Neill Forebay?
- O'Neill Forebay has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include San Luis Reservoir State Recreation Area. Public access is listed as yes.
Can I fish at O'Neill Forebay?
- O'Neill Forebay has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by California's fish and wildlife agency, so check its current regulations before you go.
Are there campgrounds on O'Neill Forebay?
- O'Neill Forebay has 3 public campgrounds from USGS The National Map within 5 km, including San Luis Creek Group Camp, Medeiros Campground, San Luis Creek Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
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Where this data comes from
Measurements for O'Neill Forebay come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Named boat-access points from the USGS National Boat Ramps inventory
Public campgrounds from USGS The National Map Structures, within about 3 miles