Foundations for a harmonious future

The river Lech was first regulated in around 1870. The early regulating structures, which protected the nearby farmland, started a basic change of character in the Lech, which then carried a high bed load. By 1930, between Landsberg and Augsburg, the Lech was fully regulated and flowing in an uniform channel. The resulting increase in depth was handled with several new weirs, but the high gradient between the weirs continued to cause erosion of the river bed. The course of the river had lost its balance, like so many others, and therefore a new phase of development began. A series of hydroelectric power plants were built along the river.

The systematic development of the Lech began after the foundation in 1940 of Bayerische Wasserkraftwerke (BAWAG) in Munich. The first steps were taken between Schongau and Landsberg — the easiest part of the river from a construction point of view. By 1950 nine submersible hydroelectric power plants had been built (in fact numbered seven to 15).

BAWAG decided at the start of the 1950s to develop the river between Fuessen and Schongau. In 1954, after four years of construction, a particularly important part of the project was completed: the head reservoir Forggensee and Rosshaupten power plant. This was numbered ‘one’ in the river series and by 1971 plants numbered two, three, four and six were also complete. Plant five had been omitted for environmental reasons. The development was continued between 1973 and 1984, when plants 18 to 23 were built below Landsberg. At the same time urgently needed regulation and improvement of the river in the area was completed.

Now the 21 BAWAG power plants (see schematic, right) between Fuessen and Ausgburg are together capable of producing 260MW. The value of this contribution to the power supply of Bavaria should not be underestimated. It is especially useful during peak hours, thanks to the possibility of increasing water discharge – and power – quickly.

Laws and regulations

The water laws of the German states are among the oldest laws in operation — the Bavarian Water Law dates back to the year 1852. Today two laws apply when building near or in water: the Federal Water Household Law, dated 1957; and the Bavarian Water Law, dated 1962. The 1935 Environmental Protection Law also remains valid. Its purpose was mainly to protect valuable natural habitats and landscapes.

Due to the recent increase in environmental awareness, this law has been supplemented with a modern set of regulations detailing restrictions for landscape planning and the consequences of such intervention for the environment. The Bavarian Environmental Law, dated 1973, is an example. Since the 1970s, many other laws have been passed regarding environmental protection.

In July 1984 the protection of nature as the basis for life was included in the Bavarian Constitution (Article 141). This is echoed by the 12 points of the European Water Charter, dated 1968.

On 2 December 1990 a law detailing compulsory environmental compatibility tests for large scale technical projects was passed. This law requires extensive early environmental studies to estimate the projects’ impact on the environment.

Environment and opposition

The first phase of development between Schongau and Landsberg in 1940 was also the beginning of opposition to the entire project. The commissioner for environmental conservation in Landsberg County said that it presented an extreme interference to a unique landscape and would have a dramatic impact on the flood forests which contained valuable pre-alpine flora.

Permission for the Lechblick plant (number 11) was granted under the following conditions:

•All structures must blend well into the countryside.

•Replanting of the river banks must consider the floral characteristics of the area and must be approved by the Department of Nature Conservation (DNC).

•Replanting must use indigenous trees and shrubs in the river banks and adjoining forests. Planting in rows or other patterns is not permitted.

Negative effects on fish spawning, caused by changes in bed load and water course, meant that restocking was necessary.

The following measures were implemented to meet the requirements:

•The head was set at 8m. This meant lower dams could be used, and the impoundments were integrated into the surrounding landscape.

•The submersible power plants were designed to have the best-possible appearance.

•Then-common paving of the embankment facing the water was replaced for long stretches with planted dams.

•The banks of the impoundments and the flowing sections were left in their natural state.

•Planting was done according to instructions from the DNC, taking into account dam safety aspects.

Environmental protection organisations raised concerns about the easily accessible reservoirs being frequented by tourists from nearby major cities like Augsburg. Continuous observation of the unfortified steep banks and the water table conditions were ordered.

The first studies concerning a reservoir near Rosshaupten were published in The water powers of Bavaria in 1907 by the Royal Department of Construction, along with several schemes for a powerhouse between Fuessen and Lechbruck.

Planning for the Lech reservoir at Rosshaupten took place in the late 1940s. Early resistance focused on:

•General disapproval of the project.

•The proposed headwater level, 783/784m asl.

•An additional project to divert the Lech through the Bannwaldsee.

•The location of the dam.

•The property required in the Schwangau area.

•The lowering of headwater level in the winter.

•The possible degradation of areas protected for their scenic and natural value.

The following changes made the project possible: •The plan to divert the Lech through the Bannwaldsee was dropped.

•The height of the headwater was set at 781/782m asl.

•Near Brunnen large areas were filled in and cultivated to replace those covered by the reservoir.

Looking back today, the reservoir has proved its function and capacity several times as it mediated dangerous flood levels. Furthermore, this fifth largest lake in Bavaria offers 1540ha of lake and over 40km of accessible beaches.

The river bed of the Lech between Landsberg and Augsburg was not stable even after supporting dams were built. The water table had dropped considerably, which meant river construction measures were necessary. The 1949 Water crisis and job creation report by Prof Kraus suggested biological renewal of arid and desertified areas near the Lech South of Augsburg. In 1953 the Commissioner for Environmental Conservation proposed that BAWAG should build power plants to restore the former water table upstream of Augsburg.

Miserable condition

In 1961-1962 the State Planning Agency of the Bavarian Ministry of Economy and Transport examined Lech plants 16 to 26, with respect to regional planning. The Forest Service approved of the proposed construction and reported that ‘the greater part of the area [in question] is in a miserable condition due to the lowering of the water table which resulted from the previous regulation of the Lech. Calling it wasteland is more appropriate than river landscape’.

Fifteen years later the Regional Planning Authority again reviewed construction of plants 19 to 22. These plants had to meet the following the requirements of the Authority:

•Maintain water quality despite the influx of industrial waste water (downstream there are reservoirs for the city of Augsburg).

•Leave the water table unimpaired.

•Conserve species variety and replace lost river woodlands.

•Present a landscape study based on ecological research including details of recreational possibilities.

•Ecologically correct replanting of the replacement areas.

To meet these objectives the following regulations were established: •Conserve woods along the river bank; replace if conservation is impossible.

•Designate areas to be protected from recreational use.

•Design new submerged areas based on ecological research, for example by extending the transition between water and land.

•Create habitats which were destroyed or impaired during earlier construction projects and can now be restored; including ponds in the embankment and inflowing streams.

•Create habitats classified as valuable by the DNC.

•Create shallow water zones as spawning grounds for reed spawners.

•Create areas for nesting and roosting grounds for various types of water fowl.

•Develop recreational areas within the impounded areas, especially in ecologically less valuable locations.

Hydraulic engineers and landscape architects co-operated closely to build the plants, creating a natural water environment. This is certainly an improvement over the geometrical appearance of the previously regulated river.

Even during the construction phase it was questionable whether plant 8a, at Kinsau, would be completed, because of its location in the Lech valley and the numerous ecological and general directives from the DNC.

The new plant on this site is intended to replace a plant dating from 1907 whose equipment is now outdated. The new plant also had to solve the problem of the discharge capacity of the weir, which was not sufficient, and the poor stability of previous constructions caused by continuous river bed erosion of the local clay.

To make things more difficult, in 1960 BAWAG had leased the old power plant and had arranged to return it to the owner – in working condition – in 2050. However, a provision in the contract allowed BAWAG to exploit the hydro power of the Lech near Kinsau for maximum energy output.

The DNC’s request for conservation of the stretch of flowing river at Kinsau shaped the project. Earlier plans for a hydro power plant at a different site had not been pursued due to this request to preserve a stretch of flowing river as far as possible.

Different disciplines within the DNC presented contradictory criteria, which greatly impeded the project. Several alternative ways of meeting the 22 or so criteria were offered, including: •Reconstruction and upgrading of existing plant components.

•Rebuilding of the old weir and canal plant.

•Rebuilding as a river power plant at one of several new locations.

•Rebuilding as a river power plant with side dam at one of several new locations.

•Rebuilding as a river power plant with side dam in the newly-designed river bed, including main dam and a small hydro power plant to utilise the remaining water in the old river bed. The chosen water capacity for the variants in this section was only 120m3/s due to the surge system bet-ween Schongau and Landsberg.

The proposed design respected all planning objectives, particularly the protection of the stretch of flowing river, and suggested a divided con-struction with a split river. Discharges of up to 500m3/s would be diverted to the redesigned and upgraded power plant tail water. Any discharge beyond this would drain through the main weir in the old river bed.

The location of the main dam, including the small hydro power plant, had to be moved approximately 600m below the existing dam at section 114+630, near the end of the clay sub-strata. This decision was based on conservation of the largest possible stretch of flowing river and on geological conditions – construction could be grounded safely in a moraine, taking advantage of its low permeability and high pressure resistance. Furthermore, the choice of this location means that about 75% of the 2km stretch of flowing river will remain untouched.

The main weir is divided into three parts, each 15m wide with 6.0m high segments. The weir is dimensioned for a discharge of 1400m3/s (100-year flood) and a rise in water level of 1.75m. Even in this extreme case one metre of freeboard is still available.

The design of the weirs and stilling basins were based on hydraulic requirements, including preventive measures for possible later erosion of the river bed. A bridge spanning the weir will be used for maintenance.

Any remaining water in the stretch of flowing river is used in the small hydro power plant, which has a double-regulated Kaplan turbine with vertical shaft. It was originally on the left bank, but is now on the right. The constant turbine action creates an attractive current for fish which are offered a way to migrate upstream through the Fischbach Ost.

The location of the main and small hydro power plants was chosen not only for construction advantages but also to continue electricity generation in the old plant for as long as possible.

The power house was constructed as a low building for a discharge capacity of 120m3/s. It has two Kaplan turbines with directly connected generators. A weir on the east of the power house has the same crest length as the main weir.

The impound area is limited by the western dam, the centre dam between the power plant and main weir, the eastern dam and the massive barrier construction. The eastern dam had to be built to protect the environmentally valuable riverbank areas along that side.

Originally, the side dams were designed as submersible dams; but due to requests from the DNC they had to be redesigned as ordinary dams. They are gravel-fill dams with an interior diaphragm wall connected to the low permeable subsoil.

The power plant tail water had to withstand a discharge of around 500m3/s. Special care was taken to design this as naturally as possible. Based on the hydraulic model the impact area at the junction of the river was extended for its protection.

The construction design briefly summarised here was approved in a public hearing. Regional planning studies for the plant and associated natural park were finalised in January 1989.

The following measures ensured the regional planning requirements were met:

•The weir was moved as far south as geological conditions allow, to enlarge the stretch of flowing river and to protect valuable areas from flooding.

•The river power plant was moved north to conserve the western inflowing stream and its wetlands.

•The weir allows a minimum of 15m3/s of water to run into the stretch of flowing river, so it can function properly.

•A fish ladder was installed at the weir to allow upstream migration.

•After completion 10,000m3 of gravel was added to the flowing river to improve the reproductive conditions for salmon.

•Lost forest areas were replaced in a ratio of 1:1.25 by replanting in the same area, preferably in immediate proximity.

•The Commission on Historic Monuments required that one of the two oldest parts of the existing power plant should be incorporated into the new plant and made functional for demonstration purposes.

•One of the aggregates was to be stored, possibly in a museum, and the old building (dated 1907) documented.

The start of construction was delayed by the need to assess the impact on nature and landscape and to plan the necessary compensation and replacement measures. It was later decided that landscape planning should be continually updated based on the newest research. This brought changes throughout the entire construction period.

Possible requests for variable water regulation and increased residual water discharge amounts also had to be considered in the design. In this connection a large-scale experiment was performed in October 1986 to test the flow characteristics, current, surface of the river bed, bank coverage, and the appearance of the discharges at 0m3/s, 5.0m3/s, 10.0m3/s, 15.0m3/s, and 20.0m3/s. The ongoing feasibility studies were then based on a residual water discharge of 20m3/s.

Fish migration paths had not been considered at previous plants. Several solutions were studied, and a natural-looking stream to the east was agreed on. As a result, the main dam and the small hydro power plant had to trade places, although this introduced economic disadvantages. Although it also created the necessary current to ensure proper functioning of the fish stream.

Historic monument

Shortly before the regional planning proceedings began, the canal power plant was added to the list of historic monuments, as a witness to the industrial development on the river Lech. The original request to restore and preserve the structure in operational condition as a museum was no longer possible. Intermediate solutions, such as preserving parts of the original installation at site, were rejected by the DNC because it favoured natural development and, once construction was complete, did not want visitors to disrupt the area. Requests to preserve some mechanical and electrical installations had an impact on the dismantling and removal and extensive planning was necessary.

The approval by the Board of Energy Control regarding the laws of developing energy resources was granted in early 1988 without complications. The water rights approval, requested in July 1988, involved the following applications:

•Approval according to article 31 of the Federal Water Law for the redesign of the Lech, the old canal and the respective embankments.

•Approval for water usage according to articles 3 and 8 of the Federal Water Law, allowing dams at the Lech as well as the withdrawal and return of water electricity production.

•Building permits.

•Authorisation of early start of the project according to article 9a Federal Water Law.

•Request for the immediate ratification of the permit according to article 80, section 2, 3. VwGO.

These final approvals will be granted in due course.

During the detailed planning phase several ecological objectives had to be considered. Most important were:

•Creation of arid sites far from the water table to allow the succession to dry and open pine forests.

•Protection of valuable arid stock and transplant of rare orchids.

•Creation of habitats and migration areas for reptiles, butterflies and other fauna through select cutback of woods and starvation of patches rich on vegetation. Loosely piled heaps of rocks and concrete chunks are to serve as refuges for reptiles.

•Development of bat habitats by extension of an attic and an old dam house as well as building bat houses.

•Creation of wetlands in the areas upstream of the dam through the raised water table.

•Extension of a hillside stream containing wild trout populations and an ecologically valuable collection of water insects and invertebrate.

•Development of a fish stream with fish migration assistance.

•Creation of gravel banks and islands to be flooded periodically which will offer a place for banks of fluvial sedimentation.

•Creation of sun-exposed gravel islands as habitats for Sandpipers, Dippers and Grey Wagtails.

•Creation of an island within the impounded area for soft wood succession.

•Piling up of clay material on the banks below the water level to create habitats for water birds, small mammals and fish.

•Nature-like reforestation, preferably outside the project area, at the request of the Department of Forestry.

Construction phase

In the first phase of construction, from July 1989 to summer 1990, the power plant and side dam were built beside the river whilst the old canal plant was still in operation. In the next phase, until the end of 1990, excavations for the new power plant tailrace were performed, retaining dams were constructed and the ecological measures within the impounded area were executed. The old power plant had to be shut down at the start of these operations.

In the final construction phase the main dam and the small hydro power plant were built in an excavation in the middle of the river. The side dam and power plant had to be available at this time for the diversion of the river.

The construction period lasted approximately three years, and the plant went into service in July 1992. The total cost of construction was approximately US$60M, of which about US$15M was spent on ecological measures.

The hope is that the new hydro power plant will create a river landscape that will integrate harmoniously into the future natural park at Kinsau.