LAKE MARKEN, The Netherlands — Marker Wadden is a lush, green, man-made archipelago in a big, gray, man-made lake. Its 25,000 square acres are meant to provide a refuge for birds and wildlife that many decades ago disappeared from this shallow body of water when it was turned fresh. Lately, it’s become a refuge for people, too.
Lake Marken is not a welcoming place. Though it’s one of the largest lakes in Europe, it’s known for its barren shore and muddy bottom. There is little public access; it’s only about 10-16 feet deep and is mostly lined with rock. The lake was a bit of an accident. In the 1930s, the Dutch government built a huge dam to block off the South Sea and build new land for people and farms, a method used to create about a fifth of the country’s land. They built levees to block the water off and planned to drain it, but ultimately that proved too costly. Walling off the brackish lake turned its water fresh, killing fish and other sea life, and creating a wasteland.
But Roel Posthoorn, director for the Marker Wadden, is trying to change that. He came up with a plan to build ring dikes and dredge sand from the bottom of the lake for a vast series of islands. The marshy islands would filter the murky, silty water, clearing it up, and create habitat for native birds and plants that had long since disappeared.
At first, people told him it was impossible.
“It’s crucial that you have people who want to reward crazy ideas; otherwise, this never would have happened,” said Posthoorn, standing in a futuristic birch bird blind overlooking the island as waves crashed on the sandy beach and birds circled overhead.
Working with his nonprofit, Natuurmonumenten, or the Dutch Society for Nature Conservation, Posthoorn helped raise about $100 million to dredge Lake Marken and build five connected islands to serve as a nature refuge and bring life back to the dead lake. The organization won a grant from the National Postcode Lottery and partnered with the Rijkswaterstaat, the Dutch equivalent of the U.S. Army Corps of Engineers, to fund the project.
Posthoorn said until that point, people had seen the lake not as a potentially beautiful resource but as a wasteland that could be transformed into something more useful — like a windmill farm or an expansion of nearby Amsterdam, which lies to the south.
Part of his organization’s goal was creating “a situation where people could visit the lake and see its natural beauty.” So far, it’s working.
Posthoorn said they’re already seeing results — the water around the islands is clearer. Silt is collecting around the archipelago and settling, which cleans the water. “Let nature do the work; it’s much cheaper,” said Posthoorn.
Engineers started building the islands in 2014, and some of the smaller ones are still under construction. But research on the environmental benefits they create is already underway, and some of those benefits are easy to observe. Cattails and reeds, for instance, are flourishing, Posthoorn said, and birds, including geese, are flocking to the islands.
A team of researchers from several Dutch universities have found that the entire food web is improving — zooplankton, small crustaceans like water fleas, are thriving and cleaning up the algae in the water, while birds and fish are feeding on mosquito and fly larvae in the shallow, marshy water.
The project has also appealed to people, who are flocking to the largest of the islands by boat during the summers. Posthoorn is happy to see the islands become a destination for nature enthusiasts and said when people visit, “they start smiling.”
For a bit of a gimmick, back in 2017, he decided to get the island designated as an official voting precinct for the parliamentary elections. Natuurmonumenten worked with the municipality to set up shipping-container voting booths and arranged for ferries from the mainland. More than 1,000 curious voters took the chance to check out the island that day.
Now, Natuurmonumenten has created detailed maps so that when visitors arrive, they don’t get lost. They’re also building some small apartments for people to rent out and stay overnight on the island, which is staffed 24/7.
This all came about because officials took a hard look at the impacts of engineering decisions made over decades and recognized they had made mistakes. One of them: leveeing off Lake Marken, which had devastating effects on the environment. The government wanted to make that right.
Jaap Zanelli is a project manager with the Rijkswaterstaat. He oversees the levee that caused the damage and acknowledged the unforeseen consequences.
The Dutch pride themselves on a millennium of water engineering. But “you can’t do it the same way” for another thousand years, Zanelli said. “You must change, because everything is changing.”
Improving the health of Lake Marken is part of a wider effort on the part of the Dutch government to deal with climate change and make up for past engineering mistakes. The Delta Commission issues an annual plan, much like Louisiana’s Coastal Master Plan, with a nearly $2 billion price tag for this year. An additional $1 billion is specifically earmarked for climate adaptation.
The plan increasingly recognizes that nature can’t simply be surmounted. “We can build the dikes higher and bigger,” said Zanelli, “but how high and how big?”
Much as the leveeing of the upper Mississippi River had unintended consequences downstream — a faster-flowing, more dangerous river, and the redirection of valuable sediment that used to build up the Mississippi delta into the hypoxic “dead zone” in the Gulf of Mexico — some coastal protection projects in the Netherlands killed off estuaries and turned brackish waters fresh.
After devastating floods killed nearly 2,000 people in the 1950s, the Dutch embarked on a massive engineering project to protect low-lying areas from storms — Deltawerken, or Delta Works. The series of dams and storm surge barriers was designed to protect the Netherlands from flooding from the North Sea.
The largest of them was the Eastern Scheldt storm surge barrier, a 2.5-mile-long sluice that closed off the sea from the Oosterschelde, an inland lake. The tides dropped and, with it, the deposits of sand, and the ecosystem changed. Fisheries died off and disappeared. In the 1970s, Dutch engineers reevaluated the barrier and ended up adapting it to keep it open.
Dale Morris, director of Strategic Partnerships at Baton Rouge’s Water Institute of the Gulf and former economist for the Dutch Embassy, led trips to the Netherlands, including one with then-U.S. Sen. Mary Landrieu, of Louisiana, after Hurricane Katrina.
He said the Dutch mindset is changing. “The idea of full control over the landscape has given way to a little bit of, ‘OK, we can't control everything,’ ” he said.
The dominant paradigm in the past had been that of man’s mastery of nature — hence the local saying, "God created the world, but the Dutch created the Netherlands." These days, however, Dutch leaders are taking a different tack.
“Living with water ... building with nature, those things are now more in vogue, because of this change in mindset that they just can't engineer themselves out of their problems,” Morris said.
Still, Posthoorn hopes that engineering the Lake Marken island will help to make up for some past mistakes and, if not, at least he’s having fun trying. After a walk across the island, Posthoorn reaches a sandy bank that sharply drops off to the lake, where waves crash on the shore.
“Let’s go for it!” he shouts, running down the bank gleefully. “Last summer, there were several days where this was completely covered with people who were just enjoying and swimming. ... I really dived into it!"
This story was produced in collaboration with the Times Picayune/The New Orleans Advocate. It is part of the Pulitzer Center's nationwide Connected Coastlines reporting initiative. For more information, go to pulitzercenter.org/connected-coastlines.
Support for the Coastal Desk comes from the Greater New Orleans Foundation and the Walton Family Foundation. Stay tuned all this week for the rest of the series.