---from http://blog.rscva.com/2006/06/14/fly-geyser-one-of-nevadas-little-surprises/
"I’d researched the geyser before heading up there and found that it’s not a natural phenomenon. The geyser was created accidentally in 1964, after a geothermal power company drilled a test well at the site. While the groundwater in the region turned out not to be sufficiently hot to be tapped for geothermal power, it did have a temperature of more than 200 degrees.
According to later newspaper reports, the well was either left uncapped or was improperly plugged. In either case, the scalding hot water was allowed to shoot from the well hole and calcium carbonate deposits began to form, growing several inches each year.
Jump forward several decades, and those deposits have become large mounds taller than an average-sized man that rise out of a field of tall reeds and grasses.
Scientists familiar with the geyser note that the green and reddish coloring on the outside of the mounds is the result of thermophilic algae, which flourishes in moist, hot environments.
Interestingly, the set of circumstances that created Fly Geyser in 1964 apparently occurred at least one time before. In about 1917, a well was drilled a few hundred feet north of the geyser. This well was also abandoned and, over time, a massive 10 to 12-foot calcium carbonate cone formed.
Today, no hot water flows from the older mound. It appears that the earlier geyser dried up when underground water was diverted to the newer one."
---from http://www.cmdrmark.com/20034.html
"Months before our trip, I tracked down the caretaker of the Fly Geyser. He asked that I contact him a day or so before we'd be in the area. We called his cell phone number but service is spotty so we simply left a message that we would be in the area and would like to shoot some pictures of the geyser. We'd try to call him later. It was around 4:00 when we drove north on a dirt road looking for an appropriate place to camp for the night. When passed a pickup truck, the driver outside securing a gate. MSO quipped that it was probably the caretaker of Fly Geyser. I chuckled saying we couldn't be that lucky as we passed by. A half mile later, the guy in the pickup is behind us so I pull to the side of the gravel road to let him pass. Instead he slows down and calls out, "Your name Mark?" Yep, MSO was right. It was the caretaker who was checking the geyser when we passed. He said that Sunday would be bad for him but if we were interested, we could see the geyser and springs now. We jumped at the opportunity, spun the RV around and followed the pickup to the gate. We followed the single lane dirt road to the end where we beheld the 1960's geyser. Streams of boiling hot water spurted from the geyser's numerous openings. The caretaker allowed us to snap photo after photo of the attraction while telling us the history of the area. After 45 minutes, I started to feel guilty monopolizing the man's time. We profusely thanked him for giving us the opportunity of seeing this awesome sight. I tried to offer him a little 'folding green' to more fully express our thanks but he refused my offer with a smile. This man's pleasure was in seeing the pleasure in the eyes of others as they beheld the sight. He's truly a class individual and a genuinely nice guy. "