They sit as lonely sentinels out on Lake Michigan. Some look like lighthouses, others like circus tents. Why are they there? How did they get out there? More importantly, what are they? 

Some know these structures as “water cribs.” Their official name is water intakes or water intake cribs. From the Jardine Water Purification Plant near Navy Pier to a DePaul drinking fountain,  the water Chicagoans consume and use for cooking and bathing starts its journey at these intakes.

“The cribs are basically the straw that brings the water from Lake Michigan into the water system,” said Megan Vidis, a communications officer for the city’s water department. “

From here, the Department of Water Management can treat and distribute the water to Chicago and 120 suburbs. About five million people rely on this system every day. 

According to Vidis and WTTW host and producer Geoffrey Baer, the story of the cribs started in the late 19th century as Chicago’s population began to boom. At the time, Chicago had no sewer system, so residents and factories dumped their waste into the Chicago River.

In the mid-1850s, water was pumped in from the lake’s shoreline. But since the river flowed into the lake, it wasn’t long before the water became tainted again. Contaminated water triggered a massive cholera outbreak that killed 1,400 people. 

Then came a civil engineer from Boston named Ellis Chesbrough. He proposed the reversal of the Chicago River. 

“First, his whole idea was to raise the levels of the streets in Chicago and build a sewer system because you couldn’t really build it underground because you were below sea level if you were underground, but all the sewage was still draining into the river and going out into the lake,” Baer said.

This is when Chesbrough proposed moving the water intakes two miles offshore.  Construction started in 1864 and Chicago’s modern water system began.

The first intake crib, Two-Mile Crib, was built on shore and floated out to its location before being anchored to the lakebed. According to Baer, this gave workers the ability to start digging 194 feet below the lake’s floor and toward shore. Back on land, the rest of the crew began digging, and the workmen would meet in the middle.

“It was an incredibly precise operation that was done basically with picks and shovels and hand cars,” Baer said. “They basically had donkey carts.” 

Joseph Schwieterman, an urban planning professor at DePaul, described the construction as a “Herculean feat.” By the time the digging parties met in the middle, they were only off by seven inches. Two-Mile Crib was then connected to the still active Chicago Avenue Pumping Station, more commonly known as the Water Tower.

After the Great Chicago Fire destroyed a huge part of the city in 1871, six more cribs were built. Today, only two, Dever and Dunne, are still active, feeding water to Chicago day after day.

“Very little infrastructure from before 1875 survives, but the cribs are an exception,” Schwieterman said. “They’ve served us faithfully for over 150 years.”

Vidis — who works at the Jardine plant near Navy Pier, where the lake water is purified — said she has stepped onto the cribs many times. Baer also got close to them while sailing since the structures were used as markers for boat races.

“Birds and spiders — and a lot of spiders,” Vidis said, when asked what it’s like to be on the cribs. “I don’t know how the hell they get all the way out there, but there are a lot of spiders. There’s (also) a fabulous view of the city.”

Before automation became standard, people known as crib tenders would stay out on the cribs similar to a lighthouse keeper. Baer described one of their tasks as using dynamite to keep the intakes free of ice in winter. There are no longer full time ‘crib tenders’ who live out on the water.

“People still go back and forth all the time,” Vidis said.

Schwieterman can see the cribs every day from his Loop campus office and during his commute.

“You could say it makes me happy that we rediscovered the glories of our lake and river after many years of neglect,” he said. “We just took our waterways for granted for many, many years. 

“Now we are rediscovering those in a big way.” 

Related Stories:

• Biden Administration to mandate limitation of ‘forever chemicals’
• ‘Go green’ this spring at Chicago’s sustainable Green City Market
• Chicago Plan Commission approves $7 billion United Center expansion