Unnamed Thermal Spring

Sonoma County, California · Near Kenwood
38.3890°N, 122.5670°W · 340 ft
73°F 51°F air · Good soaking weather 340 ft Short Walk Camping nearby (21.5 mi)

Kenwood, in the Sonoma Valley, has an unnamed spring a couple of miles out that the USGS sampled in 2003 and found tepid. The water came out in the low seventies, about what a shaded swimming pool runs, which puts it in seep territory. Nobody has noted whose land it is or if the public is allowed in, and the only name it carries is the USGS site number.

Location

A short walk off Keiser Lane, under five hundred feet, gets you there on paper. Low country, a few hundred feet above sea level, with wet winters and bone-dry summers. Some 27 inches of rain annually, nearly all of it in the cool months, and no snow worth mentioning. The owner and the access status are empty in the record, so the walk may cross private ground.

The season on the list runs December through February, cold enough air that tepid water passes for warm. Nobody recorded who controls the land, so ask around before you walk in off Keiser Lane. The 2003 sample came back fairly high in dissolved solids; the chemistry block carries the number. Camping is thin here. Oak Shores sits more than twenty miles out and it is day use anyway.

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 this spring.

Aerial view of the ground around the spring LiDAR bare-earth view of the same ground around the spring
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.

Setting
Gentle slope
The ground tilts gently up to the northwest.
Highest ground nearby
153 ft above the spring
Within a quarter mile, to the northwest
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
169 milliwatts per square meter of heat flow

That's about 2½ times the US average of 65. It's higher than at 97% 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
49°
Jan
51°
Feb
53°
Mar
57°
Apr
62°
May
69°
Jun
71°
Jul
70°
Aug
69°
Sep
64°
Oct
55°
Nov
49°
Dec
Annual Precip: 26.5 in Annual Snow: 0.2 in
Best Time to Visit
December Air 49°F · Water 73°F · +25° contrast
January Air 49°F · Water 73°F · +24° contrast
February Air 51°F · Water 73°F · +22° contrast
December offers 23°F more contrast than July
Current Conditions
51°F
ESE 0.0 mph 98% Good soaking weather
Tuesday 86° Low 52° Sunny
Wednesday 78° Low 50° Patchy Fog then Mostly Sunny 1% precip
Thursday 82° Low 51° Patchy Fog then Mostly Sunny
Friday 85° Low 52° Patchy Fog then Sunny
Saturday 84° Low 52° Sunny
Water Chemistry Sampled 2003-07-15

The water at This spring contains 641 mg/L total dissolved solids.

Higher mineral concentration for therapeutic soaking
Where to Stay

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Nearby Camping
Oak Shores Day Use Area (Ca) 21.5 mi away

Overview Nestled between Blue Ridge and Cedar Roughs east of Napa Valley, Lake Berryessa provides ample public recreation opportunities. Popular activities on and around the large, yet uncrowded lake include fishing, boating, water skiing, wake boarding, jet skiing, sailing, swimming, kayaking, canoeing, wildlife viewing, hiking, biking and picnicking. The Dufer Point Visitor Center offers year-round interpretive events and exhibits highlighting natural and cultural resources. Lake Berrye...

Reservable Yes
Reserve on Recreation.gov →
Temperature
73°F
Warm Hot Boiling
Water Temp 73°F (23°C)
Avg Air Temp 60°F
Above Ambient +13°F
Mild soaking conditions September
Access
Road Access Short Walk
Nearest Road Keiser Lane
Distance to Road 477 ft
Frequently Asked Questions
What is the water temperature at ?
has a water temperature of 73°F (23°C). This is a warm thermal spring.
Where is located?
is located in Sonoma County, California at 340 feet elevation, near Kenwood. Coordinates: 38.3890°N, 122.5670°W.
How do I get to ?
has Short Walk road access, with the nearest road being Keiser Lane (477 ft from the road).
Can I camp near ?
Yes, Oak Shores Day Use Area (Ca) is located nearby (21.5 miles away).
What minerals are in the water at ?
Water chemistry analysis shows the presence of Total Dissolved Solids. Total dissolved solids measure 641 mg/L.
Sources: USGS NWIS