The Isar River project
Ask a Münchner about the loveliest nature reserves in his or her home state and you will probably hear them name such places as far afield as the Eng Valley, the Bavarian Forest or Berchtesgaden National Park. One area of outstanding natural beauty, which they are less likely to think of, however, lies right on their doorstep—the Isarauen. These riverside woodlands stretch from Bad Tölz in the south to Freising in the north.There can be few nature reserves so close to a world-famous city and yet so unsung as the Isartal—the 28-km-long valley through which the Isar winds its way toward Munich, having originated at 5,741 feet in the Karwendel mountains just north of Innsbruck.
What makes the landscape of this originally wild river so unique is that every stretch has its own character. Take, for instance, the bird-breeding area on the gravel banks near Wolfratshausen or the steep cliff-like banks around Grünwald. This natural paradise has been under protection for almost a century.
The origin of the Isar can be traced back millions of years to the time when the Mediterranean receded and the Alps rose up out of the water. Over the last two million years, spanning at least four ice ages, enormous glaciers have formed, stretching from the Alps to the site where Munich now lies. Whilst this totally changed the course of the upper and mid-river, the lower part, some 30 km south of Munich, retained its original bed.
On its journey through the Alps and their foothills, the Isar carries a vast amount of gravel deposits, causing the river to branch out constantly in new directions, shifting the course of the riverbed time and again as it settles. When the water rises, the gravel banks are flooded, plant life is torn away and new gravel banks are created further downstream. These open banks are life-supporting for such ground-breeding birds as the river plover. Within a very short time this new terrain is colonized by numerous plants, the seeds of which have been carried down from the Alps. This explains the vast array of alpine vegetation in the Isarauen.
These fast-flowing waters have traditionally lent themselves to the transport of goods by raft. Though rafting on the Isar is nowadays restricted to pleasure trips characterized by the sound of jazz and the clinking of beer mugs, the Isar served earlier as a trade route. Until as late as the turn of last century, for instance, some 10,000 rafts, laden with all kinds of goods arrived in Munich every year until roads and rail finally put the rafters out of business.
In 1923, however, this highly-sensitive ecological system was thrown completely out of balance. It was the year the Walchensee power station went into operation—and the Isar was diverted from Krün, close to the Austrian border at Mittenwald, to Walchensee. Shortly thereafter, the River Rissach met a similar fate, with the Dürrach and the Walchen being diverted into Achensee. This effectively robbed the Isar of three important tributaries, leaving very little water to follow the natural course of the river. Ever since, not surprisingly, each dry period has led to low water levels on the Isar—the reason for building the Sylvensteinsee reservoir in 1959 and the Tölzer reservoir in 1961. These, in turn, have had the effect of collecting many of the gravel deposits and depriving floodwater of its ability to wash free the overgrown gravel banks. And so the bed of this once wild river, once feared for the strength of its currents, now most often resembles a stone desert. Recently, the Isar has hardly even been in a position to shift its riverbed, with gravel deposits being washed so far away that it is now penetrating ground moraine. The environmental problem has been heightened over the last few decades by thousands of sun worshippers from Munich descending on the gravel banks on hot summer days and large numbers of water sport enthusiasts taking to the river in rubber boats, canoes and kayaks.
This is the background against which the “Isar Plan” was born. Some 12 years ago, following a citizen’s initiative, Munich’s City Council acknowledged the need to return to the Isar some of its original features. They commissioned the Regional Office of Water Management in Munich to suggest ways of “restoring” the river in the southern part of the city. The plan they drew up is a collaboration, bringing together experts from the city’s building, planning, health and environment authorities with representatives from business and higher education. The Federal State of Bavaria is overseeing the project.
The Isar facelift is essentially a three-point plan. It aims to improve the ecological and biological function of the river, make it more attractive for leisure activities and, most importantly, protect Munich from floods. The area earmarked for redevelopment stretches 8 km from the city’s southern boundary at Grosshesselohe to the Cornelius Bridge close to the Deutsches Museum. For Münchner, this will mean an attractive new “playground” modeled on the Flaucher, the well-loved bathing and barbecue area on the riverbanks near Hellabrunn Zoo. The total cost, an estimated DM 55 million, is being split between the Bavarian state government (55%) and the City of Munich (45%).
The pilot phase of the project, inaugurated in February 2000, involved the 2.5-km stretch of river directly south of the Mariaklausensteg—the footbridge linking Maria Einsiedel with Harlaching. Here the canal-like riverbed was widened and the riverbanks flattened. This now allows gravel to gather on the banks and form islets on the bed of the river. It also has the effect of improving the passage of floodwater and creating space for landscaping work along the river. Restoration work between Marienklausensteg and Grosshesselohe was completed in the first half of this year. This winter, work will begin on the stretch of river north of Marienklause up to the Flaucher. The aim is to preserve the Flaucher whilst improving the flood barriers by making them passable for service vehicles in case of emergency.
A further objective this coming year is to increase water flow to 12 m3/s with a target of 17 m3/s after 2006. The current rate of flow—as low as 5 m3/s—is the result of channeling off most of the water to produce hydroelectric power. Power companies hit by reduced energy production are to receive financial compensation from the city of Munich. This part of the plan represents a unique attempt in Europe to restore the quality of bathing water in a river. Faced with the unsatisfactory quality of water in the Isar, especially around Bad Tölz, the mayors of the largest riverside communities between Lenggries and Moosburg have agreed shortly to equip their sewage works with disinfection systems. The Bad Tölz sewage works have already been fitted with a bacterial purification system, 90 percent of the costs being met by the state of Bavaria. Although in operation only during the bathing season, this pilot project has already proved that allowing sewage into the Isar will, in future, no longer have an adverse effect on the river’s water quality. Once all systems are up and running, it should be possible to swim in the Isar again without any health risk.
The first stretches of the river to be completely “redesigned” have already been opened to the public and are proving highly popular. Most of the remaining work on and alongside the Isar is expected to be completed in time for the opening of the “BUGA” (Bundesgartenschau), the national garden show that is being hosted by Munich in 2005. A special program of exhibitions and lectures on the “new” Isar is being organized to tie in with the event, which plans to address similar ecological issues. In the meantime, because of summer flood threats, river work will be carried out only during off-season.
Once “renaturized,” it is hoped that the Isar will be in a position to continue the process by itself. While the Isar Plan is unable to return the river to a completely natural state, it represents a significant step toward this ideal. Not only will the initiative open up new natural habitats for plants and wildlife, but it will also ensure a new lease on life for valuable green-belt land whilst responding to the desire of Münchner to relax in a safer, more natural environment without having to leave the city.
