On the third day of Mauna Loa’s historic eruption, lava began to slow down, spread out and inflate as it entered the relatively flat saddle region of Hawaii island.

Next stop: one of the Big Island’s busiest highways.

But officials said the flow, if it continues, won’t reach the Daniel K. Inouye Highway, also known as Saddle Road, for at least two days and probably later given its slower pace.

Officials on Wednesday said that while planning for the potential closure of the highway has begun, there are too many unknowns at this point to say exactly how the situation will be handled.

If the lava closes or crosses the highway, that spells trouble for Hawaii island traffic circulation. Shutting down the busy road between Hilo and Kailua-­Kona would push commuter traffic onto lightly traveled coastal routes and extend travel times from 1-1/2 hours to 2 or 3 hours.

Scientists with the Hawaiian Volcano Observatory said that if the lava flow continues on its current path, it would reach the highway near its intersection with Mauna Kea Access Road.

That location was made prominent in 2019 as the site of the standoff between Native Hawaiian demonstrators and law enforcement over the planned construction of the Thirty Meter Telescope. The proposed $2.6 billion telescope has yet to be built.

The lava flow, if it cuts off the access road, also could end up interfering with the operations of the dozen or so world-class observatories atop Mauna Kea.

Farther up on the mountain, the flow already cut off access to the Mauna Loa Observatory, a National Oceanic and Atmospheric Administration outpost that takes atmospheric measurements.

As lava spilled down the mountain Wednesday, the main source of the eruption’s longest flow continued to be Fissure 3, located at the 10,500-foot level in Mauna Loa’s northeast rift zone.

Fissure 3 lava reached the saddle area at about 7 a.m., while a smaller flow from Fissure 4 declined in productivity and appeared to be slowing down, officials said.

The lava flow Wednesday went from a speed of about 4,200 feet per hour (0.8 mph) upslope to about 106 feet per hour (0.02 mph) by midday and was about 3.6 miles away from the highway and still headed in the direction of Hilo, they said.

Scientists said their seismic-­monitoring equipment was picking up lots of earthquakes near the active fissures, which means that lava production is likely to continue.

Volcanic gas plumes were seen lofting high into the atmosphere, they said, and there were reports of Pele’s hair (strands of volcanic glass) falling in the Saddle Road area.

Hawaii County Civil Defense Administrator Talmadge Magno said officials began discussions Wednesday morning about the possibility of doing something to try to divert the flow as it approaches the highway, but those discussions didn’t go far.

Ken Hon, Hawaii­­an Volcano Observatory scientist-in-charge, said diverting or stopping the flow would be extremely difficult.

“Lava diversion is a tricky thing to do, especially on flat ground,” he said. “It really comes down to a volume problem. What we’re seeing now is — take 10 of the biggest dump trucks you can think of, we’re getting that many dump trucks of lava every second delivered by this lava flow. So if you think you can pile up stuff in front of it faster than it can deliver stuff, you’re probably wrong.”

Gov. David Ige told reporters that state and county officials, along with the Hawaii National Guard, are working to create a “planning team” to look at how to deal with the lava flow that threatens the highway.

“We’ll be looking at all options,” Ige said. “We know that we cannot turn the lava flow as it comes through the mountain.”

No human efforts — and many have been tried on the Big Island over the years — can “change the course of where the lava flows,” Ige said. “I wish there was a different answer to that. … The power of Mother Nature and Madame Pele overwhelms anything we can do.”

Meanwhile, officials were urging extreme caution for those traveling on the Inouye Highway after a car was struck Tuesday night at the 44-mile marker just after 9 p.m. Two people were transported to the hospital for minor injuries following the accident, which occurred when their vehicle was pulling back onto the main roadway after having stopped to view the volcano.

As authorities warned volcano watchers about $1,000 fines for parking along the highway, officials were working to open up a new public viewing area at the Pohakuloa Training Area.

Hawaii County Mayor Mitch Roth told the Honolulu Advertiser’s “Spotlight Hawaii” Wednesday that he was hoping to open the new viewing area later that day, but said the effort involving state and federal officials was more likely to happen in a day or two.

“I took a ride out there last night and the views are stunning,” the mayor said Wednesday morning.

Along the way, he saw plenty of people defying the parking restrictions placed on the highway due to the dangerous conditions.

“You have people who are parking right next to the highway and they’re getting out with their phones and not paying attention to where they are going. And really that’s a recipe for disaster,” the mayor said.

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Star-Advertiser staff writer Dan Nakaso contributed to this report.