Plans to tame the river Danube in Croatia so that cargo can continue to be shipped efficiently between countries have raised concerns that the changes could greatly damage precious wetlands and wildlife in the north-east of the country.
"So how did this this stretch of the Danube survive like this until now?" I ask Arno Mohl, conservation expert of the Worldwide Fund for Nature, as we paddle our orange canoe downriver.
We let our craft glide almost effortlessly with the current, past a shore thick with willows up to their willowy waists in the flood waters.
A rare, white-tailed eagle arches lazily overhead, then flaps away slowly upriver, its mind on higher things. Hook-necked cormorants ("soldiers of trouble" their name means in Hungarian) stand sentinel on bare branches, immune to the noonday sun.
"The river in Croatia and Serbia escaped massive regulation, mainly due to the collapse of Yugoslavia in the war in the 1990s," says Arno.
But now the Croatian Inland Waterway Agency wants to turn its banks into embankments, build groynes (T-shaped barriers out into the river) and straighten its course. To discipline the river, to stop it daydreaming.
On the opposite bank, the Serbian authorities have similar ideas and are waiting to see the fate of the Croatian project.
"In short, they want to make the same mistakes we made in the 1970s and 80s," Arno the Austrian explains.
Earlier this year, I watched bulldozers at Grimsing, in the Wachau region upstream of Vienna on the Austrian Danube, removing the rocks, and redigging the meanders, the oxbows (and other beautiful words in the English language) reconnecting the Danube to its hinterland.
The argument between the river transport lobby and the environmentalists is a simple one.
If the river is allowed to wander to and fro like a child's mind on the last days of school before the summer holidays, argue the engineers, forming new islands one day, destroying them the next, then the main navigable channel silts up.
The barges stand idle, unable to travel.
Give us one - ideally two - lanes of motorway down the middle of the Danube, argue the barge boys.
And the only way to do that is to "complete" river-regulation work which began in the 19th Century.
Stop meddling, reply the environmentalists.
Allow the river to swell from March to August, loaded with the spring rains and the snowmelt of the mountains of Austria and Italy, of the Engadine in Switzerland, of Germany, Slovakia, Hungary, Romania, Bulgaria and Ukraine.
Let the floodplains absorb the floods, clean the nutrients from the waters, allow fish to spawn, attract birds to feed on the fish, and flocks of tourists to admire them.
Furthermore, argue the greens, few barges actually travel this river. Adapt those that do to the river, do not adapt the river to the barges.
After paddling for three hours we turn off the main river, into a side-arm which feeds the floodplain forest.
Even the sounds change here and the shadows deepen. Branches overhang the swirling, brown waters and, through the binoculars, I watch my first kingfisher, a miracle of brilliant red and green.
Darker patches on the tree trunks show that the flood is slowly receding. Bright blue dragonflies patrol the stems of grasses, which snails climbed to escape the waters.
This was once the jealously-guarded preserve of the hunters and foresters, explains Dinko Pesic, an environmentalist from nearby Osijek. Habsburg princes and then the communist elite hunted wild boar and red deer to their bloodthirsty hearts' content.
No doubt that also helped prevent the suburbanisation of the wilderness. But now the hunters have to move over and make way for the nature conservationists, says Tibor Mikuska, of the Croatian Society for the Protection of Birds.
Caught in the middle of the debate, the new Croatian environment minister, Mihael Zmajlovic, must decide in the coming weeks whether or not to approve the river regulation.
Simultaneously, Unesco - the Scientific and Cultural Organisation of the United Nations - is expected to agree to Hungary and Croatia's request to link a string of nature parks and protected areas including Kopacki Rit, into a single biosphere reserve.
The Croatian state appears to be in the strange position of trying to preserve the nut with one hand and hitting it with a hammer with the other.
On my last morning in the wetlands, I get up at dawn to watch white-tailed eagles inspect the sunrise, and record the din of a colony of grey herons feeding their impatient brood.
For all the abundance here, some species dangle by a fragile thread. There are just 70 pairs of eagles left. The last of one particular kind of sturgeon was caught on this stretch of the Danube in 2009. After roughly 200 million years on the planet, it is very close to extinction.
"Isn't there a contradiction between preserving this as a wilderness and opening it up for eco-tourism?" I ask Tibur Mikuska.
The local boy smiles. "People like their comforts. It's too hot and humid here, and there are too many mosquitoes.
"They love to come here, but they don't stay long. They soon retreat to civilisation."
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