The investigation behind a deadly 29-car pileup on Highway 18/151 is ongoing, and at the center is a cloud of fog with no obvious origin.
University of Wisconsin Professor Jonathan Martin with the Department of Atmospheric and Oceanic Sciences says Monday morning's conditions were not conducive for fog to appear, and no fog was found on RADAR.
"For it to be so intense as to cause visibility decreases and so on from a small creek or even a small pond, that's not a reasonable expectation given those ingredients, not at all," Martin said.
Investigators are following the possibility that the fog cropped up due to the release of warm treated water, or effluent, into the Badger Mill Creek about a mile from the crash site.
Martin agrees it's plausible.
"In order to have produced something that was life-threatening for vehicles in only a local spot along the road, it really does seem that something somehwat unnatural had to have occurred in that location," he said.
The cleaned, warm water is released into the creek by the Madison Metropolitan Sewerage District continually, according to an MMSD spokesperson. Martin says the combination of warm water and the cold creek could produce the conditions necessary for fog.
The district declined our request for an interview to further describe the process.
While investigators are considering the possibility, a spokesperson for the Dane County Sheriff's Office said they believe it's unlikely, because the treated water flows into the creek on the north side of
Highway 18 even though they believe the cloud of fog came from the south.
Martin said the fog could have been created fartherdown the creek, and the wind could have blown it back to the highway.
"I'm giving a deposition to a lawyer or something, I'd have to say I have no sense of certainty... but it certainly contributes in the right direction," Martin said. "It does nothing to discourage the formation."