Let Them Swim
MUNICH The mesmerizing scene along the banks of Munichs lime-green Isar River on a recent summer afternoon made me, an out-of-towner, quiver with envy. Clusters of students, off-duty office workers, families and nude sunbathers were sprawled out on blankets with bottled beer and light meals. Every so often, a swimmer or tuber passed by, carried by the swift current. In 2000, before the climate crisis accelerated, turning summers into slogs punctuated by a slew of , the city of Munich undertook a sweeping restoration of the Isar, which flows north from the Alps through downtown and into the Danube. The 11-year, endeavor involved purifying the Isars waters, expanding its floodplains and modifying its banks to accommodate the torrential spring snowmelt. The restoration was meant to benefit flood-prone neighborhoods, as well as the rivers flora and fauna. But today the river is also an easily accessible public space that offers essential relief from the heat. I dont have a balcony, I dont have a garden, but I have the Isar, said an apartment-dwelling friend who swims there regularly. Urban residents everywhere deserve the same opportunity. If cities around the world invest in cleaning up their waterways, they will create crucial lifelines to make the hottest months more bearable in environments hit disproportionately hard by global warming. Paved surfaces absorb heat, and buildings and narrow streets trap it, putting city populations more at risk than rural ones. Healthy rivers are just the kind of green infrastructure cities need ecosystems that significantly enhance the quality of urban life. Many urban rivers arent safe for swimming because theyve been contaminated by myriad forms of pollution. One culprit is toxic from everything from pesticides to trash, which flows from rooftops, parking lots, lawns and city streets during intense rainfall. In many places, upstream farms and factories also spew fertilizers and animal and chemical waste, adding to the toxic brew. E. coli bacteria and other pathogens can spill in from sewer systems and treatment plants overwhelmed by downpours. But the experience of Munich and a handful of other cities in Europe and the United States shows that its possible to curb all of these forms of pollution, build better sewer and treatment systems and contain storm water runoff to make it safe enough for swimming. Munich and the state of Bavaria constructed 19 riverside purification stations along the Isar and its tributaries. The plants treat wastewater and during the most popular swimming months employ ultraviolet-light disinfection systems to reduce the waters bacteria count. The rivers high, concrete-lined embankments were also demolished and replaced with grassy and pebbly expanses where floodwaters could ebb and flow unimpeded. In addition to making for cooler and happier humans, the restored ecosystem has been a boon for the collared flycatcher and other birds and the Danube salmon, a species that lays eggs at the bottom of the gravel stream beds. The transformation of the Isar has been so successful that city planners from Singapore to Seoul have visited to learn from it, according to Munich officials. A few other countries in Europe now offer similarly refreshing options for dips downtown: In , swimmers and wildlife have returned to the rivers running through Basel, Bern, Zurich and Geneva since the country spent around $56 billion on new sewer systems, wastewater treatment plants and other facilities. In Berns Aare River, alongside the perch, pike and grayling fish, with waterproof backpacks. The city of Vienna also offers fantastic swimming in the clear, clean water of the Danube River. And Paris is in the midst of a major effort to in time for the 2024 Summer Olympics, by capturing excess sewage and rainwater in a large reservoir during storms. In the United States, many urban rivers are so polluted that swimming in them is illegal. But efforts to clean them are underway in New York, Boston, Philadelphia, Chicago and other cities. In Boston, the Charles River, which was once so befouled it was considered beyond saving, is now swimmable most of the time because extensive reduced illicit sewage discharges and sewer overflows. In September, the Anacostia River in Washington, D.C., will open for a for the first time in 50 years a result of infrastructure improvements to cut sewage overflow costing of dollars over 20 years. And in Portland, Ore., after an involved cleanup, its now possible to swim, fish and boat in the Willamette River. These cities are beacons that others should imitate: The investment is huge, but so is the payoff. As climate change drives ever more city dwellers to rivers, it is also . Last years drought-plagued summer shriveled many of Europes great waterways the Rhine, Danube, Loire and Po, among others by record levels. Smaller tributaries disappeared completely. The more rivers dwindle, the more saline they become, and the more inhospitable they are for life. In the worst cases, they become susceptible to toxic algae blooms. Last year, these symptoms triggered a in the Oder River along the German-Polish border. The vicious circle of the climate crisis makes river restoration all the more urgent yet ever harder to accomplish. But healthy, resilient rivers constitute a first line of defense against climate breakdown and the impact that rising temperatures will have on all our lives. Paul Hockenos is a Berlin-based writer.