• water flowing over rocks into basin

    Hot Springs

    National Park Arkansas

Frequently Asked Questions--The Hot Spring Water

1) What makes the water hot?
Water that falls as rain in the recharge or watershed area sinks about a mile deep through faults and fractures. As it goes deep into the earth, it becomes heated by the natural heat gradient of the earth and compression. The hot water then rises quickly through a fault at the base of Hot Springs Mountain.

2) Where's the recharge area for the hot springs?
The recharge area or watershed for the hot springs is the area to the northeast and east of the park, including Hot Springs Mountain, North Mountain and Indian Mountain.

3) What's in the hot spring water?

Silica (SiO2)

53.0

Bicarbonate (HCO3)

130.0

Calcium (Ca)

47.0

Sulfate (SO4)

7.8

Magnesium (Mg)

4.9

Sodium (Na)

4.0

Chloride (Cl)

2.2

Fluoride (F)

0.26

Potassium (K)

1.4

Oxygen (O2)

4.5

Free Carbon Dioxide (CO2)

9.7

Radon gas emanation amounts to 43.3 picocuries per liter. This low level of radioactivity is well within safety limits. Exposure to air allows further dissipation of the gas.

4) How hot is the water?
The average temperature for the hot spring water emerging is 143º F or 62º C.

5) How much hot spring water emerges each day?
Approximately 700,000 gallons are collected each day in the hot spring water reservoir.

6) Where do the hot springs emerge?
The hot springs only emerge at the base of Hot Springs Mountain on the western slope. They emerge through a fault and do not occur any where else in the park except in the downtown Hot Springs part of the park.

Did You Know?

black and white photo of bronze eagle on top of limestone

In 1892 U.S. Army Lt. Robert R. Stevens hired the noted Boston firm of Frederick Law Olmsted to create landscaping plans for Hot Springs Reservation, now Hot Springs National Park. Stevens rejected the firm’s plans in 1893, but some features were adopted and still survive today.