Spring In Oneill Forebay

Merced County, California · Near Gustine
37.0830°N, 121.0420°W · 223 ft
70°F 63°F air · Good soaking weather 223 ft Open Short Walk Bureau of Reclamation
Aerial view of the ground around Spring In Oneill Forebay LiDAR bare-earth view of the same ground around Spring In Oneill Forebay
Aerial LiDAR bare earth

Drag the handle to compare the two views. The orange dot marks the spring, in a frame about three quarters of a mile wide.

This is an unnamed thermal point sitting in O'Neill Forebay, part of the San Luis Reservoir State Recreation Area in Merced County, about twelve miles from Gustine. The listed name is a location description. The water is barely warm. Access is open, and the land belongs to the Bureau of Reclamation and is run as a state recreation area.

Location
28 miles from South Dos Palos, CA

Flat valley ground, low, a few hundred yards from the road. Dry country: about eleven inches of rain a year and no snow. The surrounding land is federal, managed within the San Luis Reservoir State Recreation Area, which means recreation area rules apply. The forebay itself is the reference point; the file names no road.

The file favors winter, and the climate would allow any month. The water is too cool for a soak in any real sense. Access is open. No campground and no fee are on record. Check the recreation area for day use rules.

Terrain

Aircraft with laser scanners measured this ground to within inches. The scan strips out trees and buildings, leaving the bare shape of the land around Spring In Oneill Forebay.

Setting
Open ground
Flat, open ground all around.
Highest ground nearby
2 ft above the spring
Within a quarter mile, to the southeast
Cross-section through the spring

A slice through the ground from northwest to southeast, about 0.6 miles end to end.

Elevation data: USGS 3D Elevation Program. Aerial imagery: USGS The National Map. Public domain.

Heat Below
103 milliwatts per square meter of heat flow

That's about 1½ times the US average of 65. It's higher than at 52% of the springs on this site.

Heat flow measures the warmth working its way up through the ground from deep inside the earth. Where it runs high, rain and snowmelt that seep down through cracks in the rock come back up hot.

Heat flow estimate: Stanford Thermal Earth Model (Aljubran & Horne, 2024), CC BY 4.0.

Monthly Climate
50°
Jan
52°
Feb
56°
Mar
62°
Apr
67°
May
74°
Jun
78°
Jul
78°
Aug
75°
Sep
67°
Oct
56°
Nov
49°
Dec
Annual Precip: 11.4 in Annual Snow: 0.0 in
Best Time to Visit
December Air 49°F · Water 70°F · +21° contrast
January Air 50°F · Water 70°F · +20° contrast
February Air 52°F · Water 70°F · +18° contrast
December offers 29°F more contrast than August
Current Conditions
63°F
SW 14.4 mph 54% Good soaking weather
Tuesday 89° Low 61° Sunny
Wednesday 84° Low 60° Sunny
Thursday 85° Low 58° Sunny
Friday 90° Low 60° Sunny
Saturday 90° Low 62° Sunny
Temperature
70°F
Warm Hot Boiling
Water Temp 70°F (21°C)
Avg Air Temp 64°F
Above Ambient +6°F
Mild soaking conditions September
Access
Open
Road Access Short Walk
Distance to Road 0.2 mi
Land
Ownership Federal
Agency Bureau of Reclamation
Designation SREC
Unit San Luis Reservoir State Recreation Area
Manager SPR
Protection 4 - No known protection
Frequently Asked Questions
What is the water temperature at Spring In Oneill Forebay?
Spring In Oneill Forebay has a water temperature of 70°F (21°C). This is a warm thermal spring.
Where is Spring In Oneill Forebay located?
Spring In Oneill Forebay is located in Merced County, California at 223 feet elevation, near Gustine. Coordinates: 37.0830°N, 121.0420°W.
How do I get to Spring In Oneill Forebay?
Spring In Oneill Forebay has Short Walk road access (0.2 mi from the road).
Is Spring In Oneill Forebay free to visit?
Spring In Oneill Forebay has Open access. It is managed by Bureau of Reclamation.