GeoSights: The Midway hot pots – natural hot springs, Wasatch County, Utah
By Carl Ege
Hot pots are natural hot-water springs that form crater-like depressions usually 10 to 20 feet in diameter in mounds of tufa (calcium carbonate) that are typically 3 to 10 feet high.
Several dozen active hot pots are near the town of Midway in northwestern Wasatch County. The largest hot pot in this area is the Homestead Crater (at Homestead Resort [outside link]), which is over 200 feet in diameter, 55 feet high, and the water inside the crater is over 65 feet deep. A 110-foot-long tunnel provides access to the water for soaking, swimming, and scuba diving.
The water source for these springs is from rain and snow falling on the Wasatch Range west of Midway. Although much of this precipitation ends up in streams, evaporates, or is used by plants, some seeps into the ground and becomes ground water.
This ground water slowly migrates downward along faults and fractures through the bedrock and then is heated within the earth’s interior. From depths of at least 5,000 feet, the heated ground water rises through faults and fractures to the surface in the Midway area.
Water temperature in the hot pots varies from 54 to 104 degrees Fahrenheit. In some cases, water temperature in adjacent hot pots may vary by as much as 30 degrees.
At the Homestead Crater, the water temperature remains relatively constant at 95 to 96 degrees Fahrenheit. The variability of hot pot temperatures can result from seasonal changes in water level in the hot pots and the amount of mixing of hot and cold spring water.
When the spring water rises to the surface, carbon dioxide gas is released (the bubbles you see rising in the hot pots). This changes the chemistry of the water and causes calcium carbonate to precipitate as tufa. Over hundreds of years, the tufa builds up around the springs and forms the characteristic mounds and crater-like depressions of the hot pots.
How to get there:
From the southern I-15/I-80 interchange in Salt Lake City, head 24.4 miles east on I-80 to Silver Creek Junction (exit 148).
Travel south on U.S. Highway 40 for 13.3 miles to a stop light at River Road. Turn right (west) on River Road and proceed 3 miles to Burgi Lane. Turn right (west) on Burgi Lane and travel 1.3 miles to Homestead Drive (200 West).
Turn left (south) on Homestead Drive and proceed 0.4 miles. At about 0.2 to 0.3 miles, hot pots can be seen on the right (west) side of the road. Travel another 0.1 mile, turn left (east), and proceed into the parking lot to view the Homestead Crater.
Survey Notes, v. 36 no. 1, January 2004