O'Neill Forebay
O'Neill Forebay in Merced County, California is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 2246 acres.
- Area
- 2,246 acres
- Public access
- Yes
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Why O'Neill Forebay has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For O'Neill Forebay, no water-quality sampling on record for this lake.
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by your state environmental agency and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
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, last sampled recent years. Grade methodology: LakeQuality methodology.
Watch O'Neill Forebay water quality
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Swimming Safety
Not ratedElevated nutrients
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for O'Neill Forebay
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Trophic State Index: undefined.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) |
Where to stay 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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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 2,246 acres |
| Public Access | Yes |
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
Fishing O'Neill Forebay
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. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for O'Neill Forebay?
- O'Neill Forebay in Merced County, California is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 2246 acres.
Is O'Neill Forebay safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. O'Neill Forebay is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
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.
Explore O'Neill Forebay across LakeQuality
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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
Named boat-access points from the USGS National Boat Ramps inventory