(CNN) -- Tower Rock -- a massive island in the middle of the Mississippi River south of St. Louis -- is typically surrounded by water and only accessible by boat. But as severe drought spreads across the Midwest and pushes river levels to near-record lows, people can now reach the rock formation on foot.

"The river has dropped low enough that you can walk over to Tower Rock and not get your feet wet or muddy," Missouri resident Jeff Biget told CNN. "I only remember being able to do this one other time in my life."

Photos taken by Biget show people hiking across the rocky river bed to the island tower -- a trek that poses little risk in the near-term as water levels are expected to continue to drop for at least the next two weeks.

Tower Rock can be reached on foot when the water level is below 1.5 feet at the Chester, Illinois, river gauge, according to the Missouri Department of Conservation. That gauge dropped to around zero on Thursday and shows no sign of significant recovery in the forecast.

More than 55% of the contiguous United States is in drought, according to the US Drought Monitor, which is the largest area since April. And more than 133 million people live in those drought-stricken areas -- the biggest population affected since 2016.

Severe drought covers more than 70% of Arkansas and nearly 40% of Missouri, up from just 5% a month ago. Several locations have seen record-low precipitation over the past few weeks, including Memphis, Fayetteville, Arkansas, and Springfield, Missouri. The forecast from the Climate Prediction Center is dry, with below-average rainfall in the outlook through at least October 23.

The drought's early autumn expansion in the central US has had a significant impact on the Mississippi River. In Memphis, the river was at its lowest level since 2012 this week and and its fifth-lowest on record. By next week, the forecast calls for it to decline further, to the third-lowest level on record.

More than 40 river gauges in the Mississippi River Basin are reporting low water levels, according to data from the National Oceanic and Atmospheric Administration.

Bailey White, who lives in Tennessee north of Memphis, tells CNN she has never seen the Mississippi River's water level drop this low. White says she and her family boat on the river a few times a month, but they had a difficult time putting it in on Saturday.

"I've seen the water levels drop a little and I've seen them super high -- but I've never seen them this low before," White said. "We couldn't even get our small boat on the river. We had to try five different docks until we were able to do so. It's a small boat, so it doesn't sit deep in the water, but we definitely had to pay extra attention a few times or we would've hit some sand."

Photos show how the river has contracted away from its banks. The usually mighty Mississippi looks more like a trickle in some areas, with dry sand exposed where several feet of water usually flows.

The low water levels come at a crucial time of the year for the transport of crops from the nation's heartland, CNN has previously reported. The Army Corps of Engineers has been dredging portions of the river to keep traffic flowing -- albeit at a much slower pace. Hundreds of barges and vessels have been queuing up, waiting for the all-clear to pass through the treacherously-low river.

The Consolidated Grain and Barge Company, which buys, stores and sells crops for shipping, can usually move grain on barges loaded up to 80,000 bushels, according to David Gilbert, the company's superintendent at its Greenville, Mississippi, office.

But recently the low water levels have forced the company to keep the loads far lighter, at around 55,000 bushels.

"I ain't seen it lower than it is now," Gilbert told CNN. "We're not loading right now."

Gilbert said that instead of shipping their harvests right now, many farmers are "just throwing it in their bins" and waiting for better conditions, which could still be weeks away.

But even as the supply chain crisis grows, a playful mood is taking hold around Tower Rock.

"Tower Rock, walking on the river out to it only happens every so often," Elainna Froemsdorf told CNN affiliate KFVS.

She took her grandchildren to make the hike on Monday, which was a school holiday.

"Today was no school, so it means fun grandma day," Froemsdorf said.

She tells KFVS that her grandchildren are the third generation in her family to experience walking out to the formation. And her granddaughter, Adilyn Chowder, was happy for the new experience.

"I haven't done anything like that before, and it was kind of challenging, but it was fun," Crowden told KFVS.

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