PIERRE — For decades, the Eternal Flaming Fountain on the northwest corner of Capitol Lake has been illuminating the Capitol grounds.
But recent years have shown the flaming fountain to be somewhat less than eternal. Today the flame burns only intermittently, as the supply of natural gas fueling the fire has mysteriously disappeared.
The fountain is built on top of a 1,300-foot-deep artesian well. Hot water bubbles up, 92 degrees warm and under high pressure, helping to keep Capitol Lake from freezing over during the winter. But the same subterranean reservoir supplying hot water for the lake also contains a pocket of natural gas. From the drilling of the well in 1910 until the 1950s, it supplied natural gas to heat the Capitol building and other parts of Pierre.
After an explosion, the gas well was abandoned, but in 1972, the state decided to capture the remaining natural gas to light the fountain. Gas bubbles rise up along with the hot water, feeding the flame dancing on top of the fountain. But state special projects coordinator John Moisan said for an unknown reason, the supply of natural gas reaching the top of the fountain has dwindled to almost nothing over the past decade.
“You can go down on a calm day with a bit of newspaper and light it on fire, and you can get a little bit of gas to burn,” Moisan said. “The slightest breeze puts it out, which indicates there’s not enough gas on the surface to light it on fire.”
Decades ago, Moisan said, the fountain would burn brightly even under 40 mph wind gusts.
Moisan said there are several possible explanations for the reduced flow of natural gas. One possibility is that the supply of natural gas below the city has simply been exhausted.
The water itself could also be to blame.
“The water is extremely corrosive, heavily laden with iron and sulfur,” said Moisan. “We think what’s happened is the cast-iron well casing has simply deteriorated to the point where the only thing keeping the well open is the water rushing out of the ground.”
If the corrosive water has eaten away the well casing, he said, the natural gas could simply be dissipating into the soil before it reaches the surface.
Moisan said the state has examined solutions for restoring the well, but has rejected them for now as being far too expensive. To re-line the well with metal would cost hundreds of thousand of dollars, Moisan said, and even conducting a geological survey to test the amount of natural gas present underground would cost the state money it doesn’t have in a tight budget situation.
“We don’t even know if the gas field underneath us is still viable,” he said. “We don’t think at this point it’s worth spending the taxpayers’ money to determine that. Granted, it’s a valiant effort to have a flaming fountain there, but the question is, should we spend that kind of money to make it happen?”