FINAL REPORT

European Commission Directorate General Environment

Verification of Vulnerable Zones Identified Under the Nitrate Directive (91/676/EEC)

Sweden

February 2001

Environmental Resources Management 8 Cavendish Square, London W1M 0ER Telephone 0171 465 7200 Facsimile 0171 465 7272 Email [email protected] http://www.ermuk.com FINAL REPORT

European Commission Directorate General Environment

Verification of Vulnerable Zones Identified Under the Nitrate Directive (91/676/EEC)

Sweden

February 2001

Reference 6664

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In line with our company environmental policy we purchase paper for our documents only from ISO 14001 certified or EMAS verified manufacturers. This includes paper with the Nordic Environmental Label. CONTENTS

1 INTRODUCTION 1

1.1 BACKGROUND 1 1.2 SCOPE 1 1.3 INFORMATION GATHERING 2

2 SWEDEN - THE CONTEXT 3

2.1 INTRODUCTION 3 2.2 AGRICULTURE AND WATER 4 2.3 WATER RESOURCES 13

3 GROUNDWATERS 20

3.1 INTRODUCTION 20 3.2 AQUIFER TYPOLOGY 20 3.3 NITRATES IN GROUNDWATER 24

4 SURFACE FRESHWATER (LAKES AND WATER COURSES) 29

4.1 ASSESSMENT CRITERIA FOR LAKES AND WATERCOURSES - THE SWEDISH EPA’S ASSESSMENT 29 4.2 LAKE QUALITY - ASSESSMENT 39

5 CONCLUSIONS 48

5.1 EUTROPHICATION IN SWEDEN 48 5.2 SUGGESTED ADDITIONAL VULNERABLE ZONES 49

ANNEX AGROUNDWATER MONITORING RESULTS ANNEX BMAPS ANNEX CMAP OF DESIGNATED NVZ AND SUGGESTED ADDITIONAL NVZ 1 INTRODUCTION

1.1 BACKGROUND

This Final Report details the findings of a project carried out on behalf of the European Commission - DG Environment entitled:

Verification of the Vulnerable Zones Identified Under the Nitrates Directive

Contract B4-3040/99/91954/MAR/D1

This report presents the results of the investigations carried out in Sweden.

1.2 SCOPE

This report is a review of the areas designated as Vulnerable Zones under the Nitrates Directive (91/676/EEC). The review includes suggestions for further areas that should be designated within the scope of this Directive. The investigations focus upon assessing that waters that should be identified under the Directive have been and that all Vulnerable Zones have been designated correctly and comprehensively.

Since the coastal areas of the Baltic Sea have already been designated as Vulnerable Zones under Directive 91/676/EEC, the investigations focus on freshwaters (surface and ground waters).

1.2.1 Directive 91/676/EEC

The Directive concerns the protection of water against pollution caused by nitrates from agricultural sources. The Directive has the dual objective of reducing water pollution caused or induced by agricultural sources and to prevent further pollution.

Since certain zones, draining into waters vulnerable to pollution from nitrogen compounds, require special protection, the Directive requires (Article 3) all Member States to identify waters that are affected or could be affected by pollution and designate as vulnerable zones all known areas of land which drain into these waters. The designation process should had been completed within two years of the notification of the Directive and reviewed whenever necessary, or at least every four years, to take into account changes and factors unforeseen at the time of the previous designation.

For the purpose of realising the objectives set by the Directive, Member States are requested to establish action programmes in respect of the designated vulnerable zones and which may be related to all vulnerable zones in the territory or may differ for different zones or parts of zones. Action

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 1 programmes should be established within a two-year period following the initial designation or within one year of each additional designation.

The criteria for identifying nitrate-polluted waters, referred to in Article 3(1), are given in Annex I, as follows:

1) “whether surface freshwaters, in particular those used or intended for the abstraction of drinking water, contain or could contain more than 50mg nitrate/l (if action pursuant to article 5 is not taken);

2) whether groundwaters contain more than 50mg/l nitrates or could contain more (if action pursuant to article 5 is not taken);

3) whether, natural freshwater lakes, other freshwater bodies, estuaries, coastal waters and marine waters are found to be eutrophic or in the near future may become eutrophic (if action pursuant to article 5 is not taken)”

For the scope of the Directive “pollution” is defined as “the discharge, directly or indirectly, of nitrogen compounds from agricultural sources into the aquatic environment, the results of which are such as to cause hazards to human health, harm to living resources and to aquatic ecosystems, damage to amenities of interference with other legitimate uses of water”.

Article 6 of the Directive describes the requirements for the monitoring programme that should be established for the measurement of nitrate concentrations in surface and groundwaters, as well as the assessment of the eutrophic state of freshwaters.

1.3 INFORMATION GATHERING

The following organisations were contacted in order to obtain the required information:

• the Swedish Board of Agriculture; • The Geological Survey of Sweden; • the Swedish University of Agricultural Science; • the Swedish Environment Protection Agency; • Statistic Sweden; • the Swedish Chemical Inpectorate; • Uppsala University

These organisations were identified as being the most important ones in relation to water quality monitoring and assessment in Sweden. More details on the actual monitoring programmes are provided in Section 2.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 2 2 SWEDEN - THE CONTEXT

2.1 INTRODUCTION

2.1.1 Background

Sweden is a long (1,557 km) and narrow country of 450,000 km2 and is divided into 21 counties and 288 municipalities. Forest covers about 62% of the total land area and is one of Sweden’s key natural resources. Historically, timber, pulp and paper, iron and steel have formed the backbone of the Swedish economy. Today, high-tech industry is a very large contributor to the economy.

Figure 2.1 Sweden - Administrative Divisions

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 3 2.1.2 Population

Sweden has 8.9 million inhabitants. A total of 85 % of the population lives in urban areas, the three main ones being Stockholm, Gothenburg and Malmö. In comparison to other European countries, the population density is relatively low, averaging 19 inhabitants per square kilometre.

2.1.3 Climate

The climate varies from warm temperate in the southern coastal areas to arctic-alpine in the Scandic mountain range. Northernmost Sweden extends beyond the Arctic circle and the seasonal variations in daylight are considerable throughout the country. The climate is influenced by the Atlantic gulf stream.

2.1.4 Inland Waters

There is an abundance of surface freshwater courses and lakes in Sweden. They include oligotrophic mountain rivers and lakes, turbid forest lakes, and (eutrophic) watercourses flowing through the agriculture-intensive lowland. There are a total of about 60,000 km of rivers and streams and about 90,000 lakes (< 1ha). This obviously forms an important resource as about 50% of the Swedish drinking water supply is based on surface water. Only the larger lakes and their catchment areas are taken into consideration in this study.

2.2 AGRICULTURE AND WATER

2.2.1 Agriculture - State and Pressure

Significant changes took place between the 1950’s and the mid-1990’s, mainly due to the abandonment of agricultural land (Sweionet, 2000). During this period, arable land steadily declined from 3.6 million hectares to 2.7 million hectares. At the same time, a significant reduction in pastures could also be observed: from 0.72 million hectares to 0.22 million hectares. According to Sweionet, the area of land used for grazing increased again after 1995 as a consequence of specific political measures such as the environmental grants programme NOLA and Landscape Conservation.

Increased mechanisation resulted in a shift towards the use of large machinery and concentration of cultivation in those areas where arable land is best suited to large-scale automated cultivation. Consequently, field size has increased, barriers to cultivation such as open ditches and vegetation have been removed and smaller, more remote and irregularly shaped fields have been turned over to forest or other kinds of land use. The trend in lowland plain areas has been a shift towards crop cultivation so that meadows and pastures have been turned over to other kinds of land use. In 1997, a study carried out by the Swedish University of Agricultural Sciences predicted that by 2005:

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 4 • grassland cultivation will be significantly reduced in lowland areas and seeded grassland will only be cultivated in special regions with subsidies (ie. Norrland and wooded regions in the South of the country); • cattle raising for meat will almost completely cease; • milk production will disappear from the lowland; • overall there will be a greater regional specialisation with cultivation of cereals, set aside and pig breeding in the South and grassland cultivation and milk production in the North and Southern woodland regions.

The variations in climatic conditions around the country also affect crop distribution. In the North, the main products cultivated are ley, green fodder and feed grain. The production of bread grain is concentrated in the central and southern plains. Oil seed, mostly rape and turnip rape, is also cultivated mostly in the central and southern parts of the country.

This means that the risk of eutrophication further increases in the South as land use for cereal cultivation and set aside leaches more than cultivated grassland. This shift in cultivation methods and intensification of farming activities has inevitably resulted in significant N-loads in streams draining Sweden’s agricultural land (SLU) and a significant increase in nutrient leaching (including nitrates) in both surface and groundwaters. Through a network of small watersheds throughout Sweden (JRK network) (1), it has been shown that N losses from many agricultural areas are too great and may be one of the causes for the current trophic status of surface waters in these agricultural areas. Due to differences in climate and agricultural production systems, there are large variations in N losses in different parts of the country. The calculated mean losses for the period 1984-1994 range from 6-62 kg total N/ha/y.

Figure 2.2 Gross and Net Nutrient Loads in Southern and Central Sweden

Source: SMHI

(1) Gustafson et al. (1997), Losses of N, P and Pesticides from Agriculture and Environmental Sustainability, Sveriges Lantbruksuniversitet

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 5 Figure 2.3 Land Use in Sweden

Source: Swedish EPA, 1994

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 6 Figure 2.2 illustrates the nutrient loads in Southern and Central Sweden and it can be observed that the highest loads from diffuse sources correspond to intensive agriculture areas in Västergötland, Östergötland, Orebrolän and Uppsalalän.

2.2.2 Nutrient Leaching and Agriculture

Nutrients originating from agricultural activities are one of the main causes of eutrophication of Sweden’s marine and inland waters. According to the Swedish EPA (1),the use of nitrogen fertilisers increased until about 1970 and was followed by a decrease which, in recent years, is said to be partly due to a reduction in cultivated land. However, N fertilisation per hectare is reported to have remained constant since the 1970s. According to FAO figures, the average N fertilisation rate is 64 kg N/ha (average for all crops and forests).

Compared to phosphorus, nitrogen is exchanged far more rapidly in soil systems and therefore has been supplied more continuously in order to maintain the desired crop yields. The high mobility of nitrogen in soils results in considerable leaching from arable land.

Figure 2.3 Nitrogen in artificial fertiliser and manure (T/y)

Source: Swedish EPA

Similarly, phosphorous fertilisation of arable land doubled between the 1920’s and 1970’s. This resulted in significant amounts of phosphorus seeping into local waters. Although P fertilisation has been considerably reduced and brought back to the 1920’s level, the amount of P stored in arable land is still considerable and is reported to remain undiminished.

(1) Swedish EPA (2000), Eutrophication of Soil and Water, http://www.internat.environ.se

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 7 Figure 2.4 Phosphorous in artificial fertiliser and manure (T/y)

Source: Swedish EPA

Although phosphorus is efficiently bound to soil particles, this situation presents significant risks of nutrient runoff from agricultural areas with heavy rainfalls or snow melt.

2.2.3 Eutrophication

The situation in Sweden

Eutrophication is one of Sweden’s most widespread environmental problems and occurs in both freshwaters and marine/coastal waters. According to Sweionet, attention has been drawn in recent years to the effects caused by the increased input of nitrogen to forest soils by atmospheric deposition. However, it is widely accepted that nutrient emissions from agriculture are the main reason why eutrophication has remained a serious problem in many Swedish inland and coastal waters.

The areas most affected are the intensively farmed plainlands of central and southern Sweden that, today, have most of the eutrophic lakes and rivers encountered in Sweden (see Figure 2.5). Historically, waters in these region have always been more eutrophic than in the forest areas of Northern Sweden, but the intensification of farming activities has significantly accentuated their eutrophication.

It is estimated that over 14,000 of Sweden’s 96,000 lakes show elevated concentrations of phosphorus and 20,000 of them show elevated nitrogen concentrations. In relation to marine and coastal waters, it has been recognised for several years that large areas of the Baltic and the Kattegat are suffering from severe oxygen deficiency and related eutrophication. This was reflected in Sweden’s first round of designations which identified a large

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 8 section of the Baltic as eutrophic and related drainage areas along the coast were designated as NVZ (more information about the designation process is provided in the next section).

Figure 2.5 Regions with Eutrophic Water Bodies (in green)

Source: Swedish EPA

In addition to algal blooms and changes in species composition, eutrophication of lakes and seas cause overgrowth and results in the deterioration of bathing waters. The main criteria used to evaluate the trophic state of freshwater bodies in Sweden is phosphorous content but other factors include the content of algal chlorophyll in the water column as a measure of plant production, nitrogen content and light penetration.

The criteria used by the Swedish EPA are as follows:

“ In the for lakes • phosphorus is used as a general indicator of eutrophication, • the quotient between nitrogen and phosphorus as an indicator of regulating nutrient and the appearance of nitrogen fixation including fixing cyanobacteria.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 9 • Additional criteria for nitrogen alone classify concentrations by their frequency of appearance, not by biological/biochemical effects like the two criteria above.

For assessments of watercourses, criteria are based on transports of nutrients. The area-specific losses of phosphorus and nitrogen, calculated from concentration and flow measurements (or modelling), are assessed by empirical criteria. The area- specific losses indicate the balance between fertilization, soil function and cropping and thus function as indicators for the terrestrial system. However, they also indicate nutrient load on lakes and coastal waters and have a dual use.”

It has been recognised that the main anthropogenic sources of nitrogen are agriculture and urban areas. This is shown on Figure 2.6. As a response to pressure from the agricultural sector, good agricultural practices are encouraged and include:

• postponing ploughing and other soil preparation until the spring; • sowing cereal crops in the autumn and maintaining ‘winter green’ throughout the winter. Today, the proportion of winter green reaches about 60% of arable land; • Handling of manure; • riparian strips; • environmental charges on artificial fertilisers.

However, the current designation does not seem to reflect the eutrophication problems encountered in the intensive agriculture areas around Lake Vänern (Västergötland), Lake Mälaren, Lake Hjälmaren as well as the intensive agricultural areas of northern Östergötland (as shown on Figure 2.5). This issue is one of the focuses of this study.

Figure 2.6 Anthropogenic Sources of Nitrogen

14% 5% 1%

34%

46%

Agriculture Waste Water Treatment Deposition Industry Forestry

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 10 Nitrogen or Phosphorous ?

According to the Swedish EPA, about 15 % of Sweden’s lakes have high phosphorus concentrations (≤ 25 µg/l) and can be classified as eutrophic. These include some of Sweden’s largest lakes such as Lakes Mälaren and Hjälmaren. As can be observed in the literature, it is considered in Sweden that total-P is the best indicator of eutrophication and that phosphorus is considered as the main factor limiting the level of eutrophication in freshwater lakes. According to the EEA, “in freshwaters with little or no pollution, phosphorous will always represent the most limiting nutrient”. However, it also recognises that “most lakes are phosphorous limited. However, some seem to be limited by nitrogen, possibly because of large excess in phosphorous” (1) .

In Sweden, large quantities of P are reported to have accumulated in the bottom sediment and this seeps into the water for decades, keeping it eutrophic. This was shown in a study by Hakanson et al. where the LEEDS Model was used to look at the flows and effects of P in a lake and to predict the maximum volume of phytoplankton likely to result from input and circulation of phosphorus. The model used is defined as time-dependent and generic which accounts for all major processes regulating the distribution and effects of phosphorous in lakes. Parameters included were: dissolved and particulate P, stratification, diffusion, bioturbation, suspension/advection, fishing, mixing and mineralisation. The results showed that:

• about 5% of the P contained in the active surface sediment (which accounts for 90% of the P in the lake), is transported each year to the productive surface waters; • 72% of the primary P inputs come from the in-flowing waters (natural P- flow and agriculture); • the exchange of P through sedimentation, resuspension and diffusion is very extensive.

Arguably, one of the reasons for considering P as the limiting factor in lakes may also be that P emissions are thought to be easier to regulate than N and thus P can simply be made the most limiting factor in eutrophic lakes (2) (even- though it is reported that over 20% of Sweden’s lakes have high nitrogen concentrations). This, however, is not so obvious when phosphorous has accumulated in both soil and water for a number of years and is steadily released to surface waters. The phosphorous trapped in sediment may be leached in large amounts when oxygen concentrations are reduced to low levels and if any movement of the water mass transports the dissolved P to the upper layer, secondary eutrophication will occur. This internal loading may last for many years after external loading has ceased (EEA, 1999).

As the accumulation of P in the sediment in Sweden appears to be significant (excessive), it seems that P can not be a ‘limiting’ or a ‘management’ factor

(1) EEA (1999), Nutrients in European Ecosystems, Environmental Assessment Report No.4 (2) Personnal communication, SLU, October 2000

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 11 anymore. On the contrary, such excesses in phosphorous in freshwater lakes usually implies that these have become limited by nitrogen.

Other studies (P. Cullen et al.) have pointed out the significant and complex role of nitrogen inputs. Reductions in artificial N input can stimulate the growth/appearance of blue-green algae or the release of P by lake sediments (P is absorbed into sediments at the end of the summer algal growth period and is not washed out by winter rainfall).

There also are good indications that N may be the most limiting factor in late summer (1). In other words, N and P can both be limiting factors at different periods of the year and will influence the type of plants and algae which develop. This shows that both N and P can play a role in the regulation of lake eutrophication and can both be considered as management factors. It is generally agreed that N(the sum of inorganic N which is mainly consituted of nitrates) is a better management factor for macrophytes, dinoflagellates and diatoms. Furthermore, and as mentioned above, phosphorous accumulates in both soil and water for a number of years and is steadily released to surface waters. The phosphorous trapped in sediment is leached in large amounts when oxygen concentrations are reduced to low levels and if any movement of the water mass transports the dissolved P to the upper layer, secondary eutrophication will occur. As the accumulation of P in the sediment in Sweden appears to be significant, it seems that P can not be a ‘limiting’ or a ‘management’ factor anymore.

This shows that the N/P ratio has a primary role in the type and level of eutrophication taking place in Swedish lakes, and although it is generally accepted that in lakes P is more limiting than N, N remains a symptomatic factor that influences the type of plants involved and the timing and successions of biomass production. It would be misleading to assume that reductions in N loads would not improve the trophic status of these lakes. Indeed, nitrogen must also be considered as a limiting factor as reducing the load of P alone would not necessarily result in the desired improvement in the trophic status of lakes. According to the EEA, “it is important to bear in mind that control of eutrophication by nutrient limitation should consider both nutrient concentrations [N and P] (the major engine of control) and nutrient ratios to prevent the occurrence of adverse effects”. There are good indications that both the causes of eutrophication and degree of productivity are very likely to be due to both phosphorous and nitrogen and that both factors must be taken into consideration in order to control it.

Studies carried out by IFREMER (Institut Francais de Recherche pour l’Exploitation de la Mer) (2) in Brittany (where algal proliferation from eutrophication is widespread) showed that the removal of phosphorous does not improve the situation for coastal macrophytes. Indeed, P-removal had been widely introduced for urban sewage treatment but without results. This underlines the importance of reducing nitrate fluxes.

(1) Personnal communication, SLU, October 2000 (2) "Ulva biomass fluctuations in the Baie of Saint-Brieuc, North-Brittany, France" - taken from SCOPE Newsletter

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 12 In another study by Larson (1994), it was shown that the absence of P in sufficient concentration creates an imbalance between N and P in the receiving waters (marine waters). This reportedly lead to a situation where coastal water ecosystems lose their ability to use these nutrients and where nitrogen then reaches the deeper parts of the Baltic Sea. Furthermore, the results showed that an increase in input of P led to a decrease in the export of N to the open sea while no significant changes were noticed in the quality of coastal waters. The conclusions of this study stressed the importance of N discharge reduction in order to restore nutrient balance in the Baltic.

The information summarised above suggests that the causes of eutrophication and degree of productivity are very likely to be due to both phosphorous and nitrogen and that both factors must be taken into consideration in order to control it. A study (1) showed that “25 years’ experience of lake restoration work across the world demonstrate that improvements can generally only be achieved by acting on multiple factors”.

2.3 WATER RESOURCES

2.3.1 Decision-Making

The responsibility for water management in Sweden is shared by several organisations: The Swedish EPA, the National Board of Housing, the Swedish Board of Agriculture, etc.

The County Administrative boards are responsible for the coordination of water resources management, development and policy at sub-national levels. The mandates of County Boards are supervision, permits and water protection regulations.

The most important regulations related to water management include:

• Environment Protection Act (1996); • Water Act (1997); • Natural Resource Act (1996); • Building and Planning Act (1996); • Act on Chemical Product (1996); • Act on Public Water and Waste Water Plans (1996); • Health Protection Act (1996); • Act on Management of Agricultural Land (1996); • Act concerning the Management of Natural Resources (1987).

(1) P. Cullen & C. Forsberg (1988), Assessment of Eutrophication Control Strategies, Hydrobiologica No. 170, summarised in SCOPE Newsletter (www.ceep-phosphates.org)

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 13 2.3.2 Water Sources

The largest cities in Sweden use surface water as a source of drinking water following treatment and chlorination. According to the WHO, 50% of those who are connected to a municipal source of water are supplied from surface water catchments, 25% by surface water treated by artificial infiltration and 25% by groundwater. There are about 1,800 groundwater catchments located throughout the country, 1,400 of them supplying less that 1,000 people and 160 of them supplying over 4,000. Aquifers supplying drinking water are small open aquifers (although sometimes closed) - usually glacial fluvial deposits and deltas. Groundwater is not treated. In addition there are about 400,000 private wells for permanent residents. It is recognised that one of the greatest threats to the quality of groundwaters is the leaching of nutrients from agricultural land.

WHO reports that abnormally high levels of nitrates in wells in agricultural areas have been observed and that adequate protection of groundwater catchments is essential. Although no details are provided in the WHO report, it is believed that most of the above-mentioned groundwaters are located in the agriculture-intensive areas of Southern Sweden.

2.3.3 The Freshwater Quality Monitoring Network

The report pursuant to Article 10 of the Nitrates Directives summarises clearly the water quality monitoring activities carried out in Sweden.

Water quality monitoring in Sweden is carried out through the general environmental monitoring programme and the Swedish Geological Survey's (SGU) groundwater network. Monitoring takes the form of regular, long-term studies of the state of the environment, trends, impacts and processes and is subdivided at both national and regional level into programme areas. The programme areas of relevance for this study are (a) freshwater and (b) Arable land.

(A) Freshwater

The freshwater programme monitors lakes, watercourses and groundwater and includes various subprogrammes for reference lakes and watercourses (which are not directly affected by discharges or intensive land use and which do not directly reflect the impact of agriculture on water quality). The results of such programmes are used as background values against which the level of the impact of agriculture is measured.

Reference lakes and watercourses

These programmes are designed to monitor the average annual variations and changes over time in a selection of lakes and watercourses not directly affected by discharges or intensive land use and which are representative of the Swedish situation. At the regional level, the county administrations have been carrying out environmental monitoring since 1995. A more detailed

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 14 subprogramme has also been implemented for lakes and aims to provide information on a larger number of variables and with a time resolution (including physico-chemical and biological modelling).

National inventories of lakes and watercourses

These subprogrammes are designed to establish the state of all Swedish lakes and watercourses with regard to over-fertilisation and have been carried out since 1972. The most recent survey was conducted in 1995. National inventories of watercourses were carried out for the first time along with the 1995 lake inventory. The next survey of lakes and watercourses was scheduled to take place in autumn 2000.

The subprogramme for estuaries is designed to monitor the river-borne transport of nutrients and other substances to the surrounding sea areas. It covers the large Swedish watercourses and some representative smaller streams. The measurement points are generally located upstream of population centres and industries on the estuaries and measure the transport of substances from about 85% of Sweden's water areas.

Groundwater

The SGU groundwater network aims to study regional and temporal variations in the quantity and condition of groundwater in relation to geology, topography and climate. The groundwater network is mainly used for reference purposes and monitoring. However, because the network is intended to serve as a reference, the observation areas are relatively free from the influence of point discharges and land use.

A second groundwater subprogramme aims to (a) supplement SGU's network of groundwater measuring stations and (b) to develop models for calculating transport to and loading of groundwater aquifers. Groundwater monitoring has therefore very much focused on collecting reference data. Consequently, the results obtained do not reflect the impact of agriculture on water quality to any great extent. However, it is reported that work is currently in progress on building up a database on municipal groundwater catchments with a view to examining the quality of such water supplies. This should make it possible to gain a clearer picture of the impact of land use on water quality.

Table 2.1 shows the number of measuring stations in the various freshwater subprogrammes and lists the annexes showing the location of the measuring stations for reference lakes, watercourses and estuaries.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 15 Table 2.1 Number of measuring stations in the freshwater programme

Subprogramme Number of measuring stations Reference lakes (national) 86 Reference lakes (regional) 109 Reference lakes (detailed programme) 15 Reference watercourses (national) 47 Reference watercourses (regional) 71 Estuaries 47 Groundwater approx. 100 National lake inventory approx. 4 100 National watercourse inventory approx. 700

(B) Arable Land

The Arable land monitoring programme comprises two subprogrammes aiming at examining the impact of agriculture on surface water and groundwater quality.

Representative arable areas

This subprogramme covers some 35 small drainage basins where agriculture is the dominant activity. These areas function as indicators of how water quality (water draining to streams and rivers) is affected by agriculture and changes in agricultural practices.

Observation fields

This subprogramme consists of 15 individual, underdrained arable fields. The fields are located on individual farms and form part of the normal crop rotation. Samples are taken of the groundwater and drainage water from the fields.

2.3.4 Summary of the monitoring results

The results of the monitoring carried out within the context of Directive 91/676/EEC were summarised in the report on Article 10 of the Directive (submitted to the European Commission on 7 June 2000). It can be observed below that most of the results reported focus on actual nitrate concentrations and that there is no mention of other criteria. For example, where it is known

that surface water bodies are eutrophic, NO3 concentrations are shown (as well as P as being the limiting factor) and in most case these are below 50 mg

NO3/l. However, this limit value is not a relevant criteria for eutrophication.

It is reported that the nitrate concentrations measured in reference lakes, reference watercourses and estuaries are below 50 mg/l at all locations. The nitrate concentration did not exceed 50mg/l at any site in the 1995 national inventory of lakes and watercourses (1). Interestingly it is reported that where

(1) A new national inventory will be carried out in autumn 2000.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 16 lakes, watercourses or estuaries are deemed to be eutrophic, phosphorus is considered to be the limiting factor. It is mentioned that in addition to agriculture, the discharges originate from industry, sewage treatment plants, private households (not connected to a sewage treatment plant) and fish farms. Agriculture has been estimated to contribute about one-third of phosphorus discharges to these waters.

Groundwaters in which nitrate concentrations are above 50 mg/l are reported to be isolated cases under the general environmental monitoring programme or by the SGU's network of stations. In addition it is reported that areas where these values were measured are located in a Vulnerable Zone.

The average annual nitrate concentrations in run-off water to streams and rivers was lower than 50mg/l for all the representative areas in the period 1 July 1996 to 30 June 1997. During the 1997/98 period, the average annual concentrations exceeded 50mg/l in some of these areas which, with one exception, are all located within the Vulnerable Zone. Taken as average values over a longer period (4, 7 or 11 years depending on the length of time the measuring stations have been operating), the average annual concentrations of nitrates are reported to have only exceeded 50mg/l in run-off water of one area which is located in the Vulnerable Zone. However, it is recognised that the long-term averages for some of the representative areas in the Vulnerable Zone are in the vicinity of 50mg/l.

It was reported in the report on Article 10 of the Directive that “The results from the observation fields have been published up to and including the 1995/96 agro-hydrological year. There are only preliminary data for the time thereafter, and results are still lacking for some fields. For the period July 1996 to June 1999, average annual concentrations of nitrate above 50mg/l were measured in drainage water from some of the fields. The long-term averages for drainage water exceed 50mg/l in three observation fields, two of them located in the vulnerable zone. The average annual concentration for nitrate in groundwater over the same period exceeded 50mg/l in one field in one year. Taken as an average over a longer period, this level has not been exceeded in groundwater in any field, according to the preliminary data “.

Areas which are known to be problematic are the counties of Skane and Halland and the region around Lake Malaren. As mentioned in the Article 10 report: “Of the freshwater lakes, Ringsjön has been notified under Article 3(1) as it was deemed to be eutrophic. Nitrate concentrations in Ringsjön are excessively high. The phosphorus concentration, which is considered to be a limiting factor in the lake, is normal. The total nitrogen concentrations in the lake are often higher in the winter months”.

2.3.5 The Designation Procedure

Sweden has notified, under Article 3(1), the coastal areas of the Baltic Sea such as the Kattegatt and Skagerack, Laholmsbukten and Ringsjön. The location of these areas is shown in Figure 2.6. As reported by the Swedish authorities, and based on the results summarised above, these areas have been identified with reference to Category A.3 of Annex I to the Directive. The criteria of Annex I B

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 17 to the Directive were also reported to have been taken into account in identifying waters in accordance with Article 3(1).

The available information seems to indicate that the identification of Vulnerable Zones very much focused on the eutrophic waters of the Baltic. Only 1 freshwater lake was designated as a Vulnerable Zone and this seem to have been done on the basis of it’s high NO3 concentration (> 50 mg/l) and related eutrophic conditions. It seems that the reasoning behind the designation procedure is that phosphorous is considered to be the limiting factor for freshwater eutrophication and that, consequently, these were not taken into account for designation under the Directive, except where nitrate concentrations were very high (in relation to the 50 mg/l limit).

As discussed in Section 2.2.3, this does not seem to be entirely justified and it seems that all eutrophic waters bodies located in intensive areas of agriculture should be taken into account. Furthermore, according to the Swedish EPA’s indicators, background N levels in Swedish lakes are < 300 µg N/l (Class 1). This suggests that lakes with N concentrations above 625 µg N/l (Class 3 - which is considered high) should be considered as a threatened by N eutrophication if no action is taken and should therefore be considered for designation under the Nitrates Directive.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 18 Figure 2.6 Designated Nitrate Vulnerable Zones

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 19 3 GROUNDWATERS

3.1 INTRODUCTION

This section presents an assessment of the quality of groundwaters in Sweden. The first section will present a classification of groundwater in Sweden based on hydrogeology and geographic regions. The following section will assess the quality of groundwater in relation to specific criteria such as nitrogen.

3.2 AQUIFER TYPOLOGY

As the chemical characteristics of aquifers can vary significantly according to the geographic region and hydrology, the Swedish Environment Agency has classified them in order to facilitate comparison and interpretation.

3.2.1 Nine Geographic Regions

The nine geographic regions described below are shown on the map in Figure 3.1. The map in Annex D of this report shows the location of Sweden aquifer.

A. South Sweden sedimentary bedrock

Sedimentary rocks in the province of Skåne and the Baltic islands of Öland and Götland. Soils and rocks weather readily, and thus offer strong resistance to acidification. High natural levels of sulphate may be present.

B. South Sweden highlands

Pre-Cambrian bedrock above the highest coastline, from Skåne north to southern Närke (approximately on a level with Lake Vättern). Does not weather very readily, and soils offer little resistance to acidification. Sweden’s heaviest precipitation of acidifying substances occurs in the western part of this region.

C. West and southeast coasts

Pre-Cambrian bedrock below the highest coastline, along present-day west and east coasts; includes the sandstone of Kalmar Sound. These rocks are also slow to weather. But their location below the highest coastline, with deposits of clay and other fine-grained sediments, increases resistance to acidification. High natural levels of chloride occur along the coasts, and in areas with residual ancient sea water. Heavy precipitation of acidifying substances.

D. Central Sweden sedimentary bedrock

Sedimentary bedrock in Västergötland, Östergötland and Närke. Features are comparable with those of Region A.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 20 E. Central Sweden lowlands

Pre-Cambrian bedrock around Lake Vänern and to the east of Lake Vättern. Rocks and soils do not weather readily. Location below the highest coastline, with deposits of clay and fine-grained sediments that increase resistance to acidification. High natural levels of chloride occur along shorelines, and in areas with residual ancient sea water.

F. Limestone-influenced areas of Uppland region

Pre-Cambrian bedrock, but soils contain limestone particles due to their origins in the sedimentary rocks of the northern Baltic. Resistance to acidification is therefore strong, and it is further increased by the clays and fine-grained sediments associated with location below the highest coastline. High natural levels of chloride along shorelines, and in areas with residual ancient sea water.

G. Norrland coast

Pre-Cambrian bedrock below the highest coastline. Rocks and soils do not weather readily. But location below the highest coastline, with deposits of clay and fine-grained sediments, increases resistance to acidification. High natural levels of chloride along shorelines, and in areas with residual ancient sea water.

H. Sedimentary bedrock in Dalarna and Jämtland regions

Sedimentary bedrocks in the western region of Jämtland, and in a ring including Lake Siljan. Rocks and soils weather readily, thus offering strong resistance to acidification. High natural levels of sulphate, primarily in certain parts of Jämtland. High natural levels of chloride are not common, even though the "Siljan Ring" lies below the highest coastline.

I. Pre-Cambrian bedrock in Norrland, in areas above highest coastline

Pre-Cambrian bedrock above the highest coastline, from Dalsland in the southwest to the northern tip of Sweden. Rocks and soils do not weather readily. Little resistance to acidification, but limited precipitation of acidifying substances. Bedrock in western Dalarna is especially slow to weather. In the northernmost section, there are extensive peat bogs which can lead to oxygen depletion of the water, as well as to high levels of iron and manganese.

As can be seen by comparing Figure 2.3 and Figure 3.1, the intensive agricultural areas are mainly located on the :

• Southern sedimentary bedrock; • West coast; • Central lowlands around lakes Värnern, Vättern and Mälaren • Sedimentary bedrocks of central Sweden

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 21 Figure 3.1 Geographic Regions of Sweden

A. South Sweden sedimentary bedrock B. South Sweden highlands C. West and southeast coasts D. Central Sweden sedimentary bedrock E. Central Sweden lowlands F. Limestone-influenced areas of Uppland region G. Norrland coast H. Sedimentary bedrock in Dalarna and Jämtland regions I. Pre-Cambrian bedrock in Norrland, in areas above highest coastline

3.2.2 Five Hydrogeological Types of Aquifer

Even within the same geographical region, the characteristics of groundwater may vary widely, depending on the hydrogeology of the aquifer. For that reason, the classification system employs five hydrogeological categories of aquifer.

Aquifer Type 1: Crystalline bedrock

Crystalline bedrock consists primarily of ground-level gneisses and granites, which may either be exposed or covered with soil. In this type of bedrock, groundwater is stored in fissures. In most cases, the water table is only a few metres below the ground surface. The aquifer is often a mosaic of bedrock projections separated by shallow layers of soil and soil-filled depressions; the latter may be covered by peat. Replacement of the groundwater often takes a long time, resulting in high alkalinity and low levels of iron. At great depths,

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 22 iron levels are often higher due to lack of oxygen (low redox potential). Heightened levels of iron may also be caused by large removals of groundwater, which can result in the addition of more groundwater from peat bog areas.

Aquifer Type 2: Sedimentary bedrock

Consists primarily of sandstone, limestone, shale and slate; usually covered by deep layers of soil. The water is stored in the pores of bedrock, in the seams of the various sediments, and in fissures. Due to the normally high concentrations of calcium in the rocks, the groundwater contains high levels of basic cations (including those of calcium and magnesium) which offer strong resistance to acidification. In many cases, high concentrations of sulphur lead to high sulphate levels and/or a lack of oxygen, with high levels of iron and manganese as a result.

Aquifer Type 3: Moraines and fluvial deposits

"Open" aquifer systems, through which water tends to circulate rapidly. In moraines, the water table is usually near the ground surface. Fluvial deposits (left by rivers and other flowing water) are located below the highest coastline near glacial meltwater deposits and moraines. They may include gravel, sand and silt, and are often no deeper than 1-2 metres. Due to the rapid circulation of water, most basic cations have leached from the aquifer and overall salt concentrations are very low. This kind of groundwater is sensitive to acidification.

Aquifer Type 4: Glacial meltwater deposits

"Open" aquifers in accumulations of sand and gravel located in ridges, deltas, terraces, etc. The largest groundwater reserves are often formed in such deposits. Similar types of aquifers occur in the sediments of glacial lakes, and around shallow wells in river sediments. Due to the coarse composition of such deposits, precipitation infiltrates rapidly; the water table may therefore be very deep. Even though the water is relatively fast-moving, it usually remains in the aquifer for a long time.

Aquifer Type 5: Enclosed aquifers

An "enclosed aquifer" is one located beneath a layer of clay or some other material with very low permeability. Such aquifers may comprise, for example, moraine or glacial meltwater deposits. They are located beneath valley floors and other low-lying land. Recharge to these aquifers occurs some distance away, often on higher ground. Also included in this category are deep wells in river sediments, and wells in coarse deposits located beneath impermeable layers of fine-grained moraine. Water often remains in enclosed aquifers for a long period of time, and adjacent fine-grained sediments may have high levels of calcium. This means that, in general, the water has high levels of basic cations and strong resistance to acidification. There is often a lack of oxygen, leading to high levels of iron and manganese. The fine-grained sediments lying above usually make good cropland; but despite the fact that

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 23 they are highly impermeable, there remains some risk that nitrogen from fertilisers, pesticides and herbicides may penetrate down into the groundwater.

3.2.3 Thirty-six regional types

The aquifer types can be sub-divided by region. With five types and nine regions, there are theoretically 45 regional types of aquifer. However, some combinations do not occur in reality, and this classification is therefore limited to 36 regional types. All well-water analyses carried out and recorded by the Swedish Geological Survey have been sorted according to this classification.

3.3 NITRATES IN GROUNDWATER

3.3.1 Introduction

As reported in other sections of this report, nitrogen is highly mobile in soil and, as a result, nitrogen leaching from agricultural soil is extensive. The result is surplus nitrogen ending up in groundwaters. Such situations have gradually arisen in central and southern Sweden. According to the Swedish EPA, about 100,000 people in Sweden today are dependant on drinking water with nitrate concentrations >10 mg N/l (1) . Such areas, however, are located in the agriculture-intensive areas of Southern Sweden which have been designated as Nitrate Vulnerable Zone during the first round of designations.

It must be noted that there are many private wells where high nitrate concentrations have been recorded. These, however, usually consist of a single measurement which may not be representative of the water quality throughout the rest of the year. Such measurement were included in the database anyway (see Table 3.2) in order to have a better territorial coverage.

3.3.2 Water Classification

Table 3.1 presents the different classes of nitrogen levels which have been

defined in Sweden. It can be noticed that the upper EU limit for NO3

concentrations in groundwater is 50 mg NO3/l and that Sweden considers

very high concentrations to be in the order of 44 mg NO3/l.

Table 3.1 Nitrogen Levels

Class Nitrogen Levels NO3-N (mg/l) Description 1 very low < 0.5 Normal level for forest land 2 low 0.5 - 1

3 moderate 1 - 5 (4.4 - 22 mg NO3/l)

4 high 5 - 10 (22 - 44 mg NO3/l) Not uncommon on farmland

5 very high > 10 (> 44 mg NO3/l) Source: EPA, 2000

(1) N is nitrate-nitrogen. 11.3 mg N/l is equivalent to 50 mg NO3/l

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 24 Table 3.2 Nitrogen Class of Sweden’s Aquifer Type (in percentage)

Aquifer Type 1: Crystalline bedrock Nitrogen Class 1 2 3 4 5 Region percent B South Sweden Highlands 676195 2 C West and South-east coast 81 8 8 2 1 D Central sedimentary bedrock 84 3 9 2 2 E Central Sweden lowlands 806112 1 F Limestone-influenced areas of upland 73 8 16 2 0 G Norrland coast 894610 H Sedimentary bedrock in Dalarra and6772150 I Pre-cumbrian bedrock in Norrland 75 7 18 1 0

Aquifer Type 2: Sedimentary Bedrock Nitrogen Class 1 2 3 4 5 Region percent A South Sweden sedimentary bedrock768113 2 D Central sedimentary bedrock 86 2 7 2 2 H 7314102 2

Aquifer Type 3: Moraine and Fluvial Nitrogen Class outwash 1 2 3 4 5 Region percent A South Sweden sedimentary bedrock 28 7 31 10 24 B South Sweden Highlands 29 7 41 14 9 C West and South-east coast 656179 3 D Central sedimentary bedrock 43 4 34 13 4 E Central Sweden lowlands 59 13 20 7 1 F Limestone-influenced areas of upland 36 15 43 6 0 G Norrland coast 636252 3 I Pre-cumbrian bedrock in Norrland 67 6 18 3 4

Aquifer Type 4: Glacial meltwater deposit Nitrogen Class 1 2 3 4 5 Region percent A South Sweden sedimentary bedrock 25 4 46 13 13 B South Sweden Highlands 40103213 4 C West and South-east coast 18 12 .8 19 12 D Central sedimentary bedrock31253110 2 E Central Sweden lowlands 678195 1 F Limestone-influenced areas of upland 58 21 21 0 0 G Norrland coast 5943700 I Pre-cumbrian bedrock in Norrland 71 4 21 4 0

Aquifer Type 5 Enclosed Aquifers Nitrogen Class 1 2 3 4 5 Region percent A South Sweden sedimentary bedrock36422929 C West and South-east coast 605265 3 E Central Sweden lowlands 52 11 24 8 5 F Limestone-influenced areas of upland 18 3 58 18 3 G Norrland coast 53132210 3

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 25 The Swedish National Food Administration recommends that the levels of nitrate nitrogen in drinking water should not exceed 1 mg/l. However, water with concentrations up to 5 mg/l is considered as drinkable but with reservations. Concentrations above 10 mg/l are considered to be unhealthy. About 11,000 wells were monitored and included in a reference database by the Swedish Geological Survey. The results are summarised in Table 3.2.

The above table shows that bedrock aquifers (aquifer type 1 and 2) usually have low nitrates levels (class 1 and 2). The aquifers with the highest nitrate concentrations are the open aquifers in moraine, fluvial outwash and glacial meltwater deposit (type 3 and 4). It can also be noticed that these areas where the highest concentrations are observed are all located in southern and western Sweden ( south Sweden sedimentary bedrock and south Sweden highlands) where intensive agriculture is taking place. These areas have already been designated as Vulnerable Zones. Aquifers of type 5, which are often associated with agricultural land, also show nitrate problems in southern Sweden.

It can also be observed that a significant number of aquifers have been classified in the Nitrogen class 3 (4.4-22 mg NO3/l), Class 4 (22-44 mg NO3/l) and Class 5 (< 44 mg NO3/l). According to the Swedish classification systems and due to the fact that concentrations > 0.5 mg N/l (2.2 mg NO3/l) may be regarded as “the result of some non-natural effect” and “as a fairly certain indication of N leaching from farmland …”), these should be considered as threatened by nitrogen and eutrophication and should be taken into consideration for designation as Vulnerable Zones.

However, data for these aquifers were not included in the monitoring results provided by the SGU (see Section 3.3.3). The reason for it seems to be that this database, the results of which have been summarised in Table 3.2, does include data from private wells which are usually located in remote areas and which often consist of a single measurement (ie. no time series) (1). This means that, where no time series are available, a seldom measurement showing high nitrate concentrations is not necessarily representative of the actual situation. However, this data was included in the database in order to have a better geographical coverage.

It also appears that the monitoring results which have been provided and which are discussed in the next section (and included in Annex A) are all those for which timeseries are available. It appears that this monitoring network is mainly aimed at monitoring the effects of N deposition and the stations are therefore often located in remote areas with no (or little) local pollution. This seems to result in the monitoring in agricultural areas being infrequent (and sometimes results consist of a single measurement). This also suggests that frequent monitoring in agricultural areas is required and the monitoring network extended.

(1) Personnal communication, SGU, December 2000

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 26 3.3.3 Monitoring Results

Monitoring data (as received from the Geological Survey of Sweden and included in Annex A of this report) show that, in comparison with other European countries, Sweden’s aquifers have low nitrate concentrations (> 1

mg NO3/l in most cases). As defined by the Swedish Environmental Protection agency, “As a reference value for nitrate nitrogen, a concentration of 0.5 mg/l has been chosen. The natural level in groundwater does not exceed that amount, and concentrations above 0.5 mg/l can be regarded as a fairly certain indication of nitrogen leaching from farmland, nitrogen-saturated forest land and point sources. ”.

Taking the limit value for nitrate into account (as defined in the Nitrates Directive), only two aquifers present high nitrate concentrations (ie. > 40mg

NO3/l) which, strictly speaking, do qualify for designation under the Nitrates Directive.

Table 3.3 Aquifers with high Nitrates Concentrations

Station Date Nitrates Coordinates Comments

(mg NO3/l) X Y 85 1 95-03-23 50.149 6276844 1325039 Type of station: 95-11-09 43.183 spring 96-04-16 39.822 96-10-03 48.139 Type of soil: 97-04-09 38.086 sand 97-10-01 9.273 98-04-16 42.696 99-03-24 36.142 99-10-05 39.645 2 1 95-03-26 15.540 6186992 1355440 Type of station 95-11-08 56.500 spring 96-04-13 53.683 96-11-15 82.638 Type of soil: 97-04-10 50.840 sand 98-04-03 42.399 Source: SGU 2000

These aquifers are located near the coast in southern Sweden in areas of very low N retention ( 0-20%) and nitrate leaching is evidently a significant problem for both aquifers. However, as can be seen in Figure 3.2 these are located in areas already designated as NVZ under the Nitrate Directive.

Consequently, only the data provided by the SGU could be taken into consideration in this study. It is however recommended that the coverage of the monitoring network should be extended to the agricultural areas of south central Sweden.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 27 Figure 3.2 Location of Aquifer 2(1) and 85(1)

85:1

2:1

Source: SGU

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 28 4 SURFACE FRESHWATER (LAKES AND WATER COURSES)

4.1 ASSESSMENT CRITERIA FOR LAKES AND WATERCOURSES - THE SWEDISH EPA’S ASSESSMENT

4.1.1 Introduction

The Swedish EPA has reviewed a series of key indicators which provide a number of different measures of general water quality. In most cases, the measures do not refer to any specific environmental problem but rather to the state of the ecosystem in general and to external effects to which a body of water may possibly be exposed. The results of this review are summarised in the following section.

4.1.2 Assessment Criteria

In its assessment of lakes, the Swedish EPA uses phosphorus as the general indicator for eutrophication, the quotient between nitrogen and phosphorus as an indicator of regulating nutrient and the appearance of nitrogen fixation, including fixing cyanobacteria. For the assessment of running water, criteria are based on transport of nutrients. As reported by the EPA, the area-specific losses of P and N calculated from concentrations and flow measurement are assessed by empirical criteria and indicate the balance between fertilisation, soil function and cropping. It also indicates nutrient load on lakes.

The preferred period for nutrient assessment is reported to be from May through October (6 samplings). Samples are usually taken from the epilimnion.

Table 4.1 Nitrogen in Lakes

Class Level Total Nitrogen concentrations (µg N/l) 1 low < 300 2 moderately high 300 - 625 3 high 625 - 1250 4 very high 1250 - 5000 5 extremely high > 5000

Table 4.2 Nitrogen - phosphorous quotient (N/P) in lakes

Class Level Total N/Total P 1 Surplus of N >30 2 N/P in balance 15 - 30 3 Moderate N deficit 10 - 15 4 Large N deficit 5 - 10 5 Very large N deficit < 5

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 29 As can be seen in the map below, areas with relatively high nitrate

concentration (> 10 mg NO3/l) are located in Southern Sweden (already designated as an NVZ), around Lake Mälaren and around Lake Värnen. Consequently, the following sections will focus on these areas, as well as on other areas of intensive agriculture (eg. northern Östergöland).

Figure 4.1 Annual Average Nitrate Concentrations in Rivers

Source: EEA (1999)

4.1.3 Nitrogen Discharges and Retention

Nitrogen load

The Swedish EPA carried out some work aiming at estimating the significance of N discharges from agricultural areas (1). In order to derive estimates, the amount leached from unfertilised ley was used to represent a natural background load and provided a way to calculate the anthropogenic leaching losses. The results obtained are illustrated in Figure 4.1. It shows estimated N discharge per square kilometre without deduction for retention.

(1) Swedish EPA (1997), Nitrogen from Land to Sea, Main Report, Report 4801

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 30 The areas which were identified high N discharges (within areas of intensive agriculture) are:

• Skåne and the coast of Halland (already designated as NVZ); • The plain districts of Östergötland and Västergötland; • The Lake Mälaren region.

It is reported that the Swedish agricultural sector has reduced its anthropogenic N load from about 32,000 tonnes in 1985 to about 24,000 tonnes (25%) in 1995. This decrease is reported to be primarily due to changes in crop distribution, better nitrogen utilisation on the farm and reduced arable land. However, according to the EPA, about 45% of the nitrogen discharges caused by human activity which reach the sea via watercourses come from agriculture. This clearly indicates that measures must be taken in order to reduce the impact of agricultural activities on the trophic conditions of both marine and freshwaters.

Nitrogen Retention

Retention is defined as immobilisation or degradation of nutrients in aquatic systems and soil by sedimentation, plant uptake or denitrification. Within the context of this study, nitrogen retention occurs during transport towards the sea (ie. from source to sea). Such retention will occur in both water and soil/sediments and will be greater in waters with a long turnover time. Also, nitrogen discharges far inland are more affected by retention and, therefore, a smaller proportion will reach the sea. Retention will also be smaller for non- point sources. According to the Swedish EPA, the total N load to the sea is reduced by about 20% by retention.

Studies on hydrochemical transport have been carried out for several years at the Swedish Meteorological and Hydrological Institute. Lately, their work has focused on nitrogen transport to the Baltic sea as the Baltic suffers from eutrophication and the “prevalent opinion is that the problem is caused by high nitrogen loads” (1) . As reported by SMHI, the HBV-N model has been used in the national decision making process for best management practices in southern Sweden (160 000 km2) in 1995, at the request of the Swedish EPA and the Swedish Government. Calculations of nitrogen leaching were made regarding retention in the freshwater system, net transport to the sea, and source apportionment for the period 1985-1994.

According to the results from the model, diffuse pollution is normally retained by 10-25% before entering the river network and lakes normally reduced nitrogen transport by 30-40 kg ha-1 lake year-1. As there are numerous lakes in that region, it is equivalent to saying that, during the period taken into account in the model, about 45% of the annual gross load was reduced during transport. However, temporal and spatial variations are considerable and retention in agricultural areas is often much lower.

(1) SMIH, Hydrochemical Modelling sourced from www.smih.se

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 31 Box 4.1 The HBV-N Model

As reported by the SMHI, the hydrological HBV model includes parameters that are calibrated against measured time-series of concentrations. At present, the calculations are made from the root zone for transport in groundwater, rivers and lakes within subbasins which are coupled into large river systems. The schematic structure of the model is shown below (as presented on www.smhi.se/sgn0106/if/hydrologi/hydchem.htm).

The model was described as follows: “Root zone concentrations are assigned for various land-use categories (i.e. arable land, forest, pasture and other land) to the water percolating from the unsaturated zone to the groundwater. This soil leakage is mixed with emissions from rural households and atmospheric deposition on water surfaces. Then the runoff from the subbasin is mixed with the water from upper subbasins, emissions from industries and effluence from municipal treatment plants, and lake water with corresponding atmospheric deposition, if lakes are present. If there is no lake in the subbasin, the water and nitrogen sources are just mixed and passed on to the lower basin. Additionally to the mixing of water with different concentrations, empirically based relations between physical parameters and concentration dynamics reflects the turn-over processes that may affect the nitrogen load during the residence in groundwater, rivers and lakes. The present version of the nitrogen model has separate routines for simulations of inorganic and organic nitrogen concentrations, and the calculations are made numerically on a daily time-step for each subbasin”. In relation to N retention, results were obtained by daily simulations which were made in 3725 subbasins with calibration against measured time series at 722 sites. Source: SMHI

As mentioned above, it was estimated by the Swedish EPA that over 20% of the nitrogen load is retained before reaching the sea. Of course, point source discharges near the coast (eg. urban waste water treatment) will not be greatly affected by retention. On the contrary, retention will be much greater for inland diffuse sources for which a greater proportion of the nitrogen is retained between the source and discharge at sea. This is illustrated on Figures 4.4 and 4.5.

A Study on the Bjerkreim River

A study on N inputs and losses to streamwater was carried out in south- eastern Sweden during the period 1993-1995 in 19 subcatchments of the Bjerkreim river (685km2). It showed that the total N fluxes in the main river outlet were 8.1-10.7 kg/ha/yr. Of this, 70% was estimated to be of atmospheric origin. Average N retention of total N (calculated as 1- (Nout/Nin)) was 0.75-0.90 in forested catchments, 0.65-0.70 in heathland and

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 32 0.55-0.70 in mountainous areas. Possible hypotheses for the relatively high N leaching may be:

• low N-uptake capacity due to shallow soils, sparse vegetation and short growing season; • losses due to hydrological events; • limitation of vegetation growth by other factors than N (eg. P).

The conclusions of the study were that leaching of nitrates in southern Sweden is a widespread phenomenon leading to increased acidification and altered nutrient balance in the aquatic environment. This can be confirmed by Figure 4.2 which shows the very low retention potential in southern Sweden. It clearly shows that all coastal areas are characterised by very low retention and that the retention potential increases towards inland areas.

Conclusions

Figure 4.3 shows the actual retention of N from non-point sources, as calculated by the Swedish EPA. Figure 4.5 shows anthropogenic leaching from agricultural land and it can be observed that the same regions are of concern. These areas also correspond to the areas classified as farmland (see Figure 2.1 of this report).

However, it can be observed that the retention around the main lakes (ie. Mälaren, Hjalmaren,Vättern and Vänern) is very high and, as much as it reduces the flow of nutrients reaching the Baltic (and hence the impact of diffuse pollution on trophic status of the Baltic), it must have a direct effect on the inland freshwater environment. Indeed, the retention values shown include retention in both soil and water. As shown on Figure 4.3 and 4.4, retention in the areas of the main lakes ranges from 50-75% (and even higher around lake Vättern). Since about 10-25% is retained by soil, this suggest that the remaining 25-50% enters the lake and river network and is retained there. As mentioned, this reduces the N load reaching the sea but it will undoubtedly affect the freshwater ecosystem in those region where background N levels of pristine waters are >300 µg N/l.

4.1.4 Limiting Factor

As discussed in Section 2, phosphorous is generally considered as the limiting factor for the eutrophication of freshwaters in Sweden. However due to the level of accumulation in sediments, P cannot really be considered as a limiting or ‘management’ factor and there is evidence that both nitrogen and phosphorous should be taken into account. Therefore, the nitrogen content of freshwater lakes and rivers have been taken into account and it has been considered reasonable to assume that, within the context of this study, water bodies classified in pollution degree classes 3-5 are to be considered as Vulnerable and at risk from N eutrophication (class 3 implies a doubling of the background N value).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 33 Figure 4.2 Anthropogenic nitrogen discharges

Source: Swedish EPA

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 34 Figure 4.3 Nitrogen Retention Potential in Sweden (soil + lake/river network)

Source: SMHI

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 35 Figure 4.4 Retention of Nitrogen on its Way to the Sea

Source: Swedish EPA

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 36 Figure 4.5 Anthropogenic Leaching from Agricultural Land

Source: Swedish EPA

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 37 Region of Göta Älv - Klarälven

The region is characterised by good nitrogen retention, mainly due to Lake Vänern and areas upstream of it. It has been estimated that the anthropogenic load accounts for 90% of the total nitrogen load. An interesting fact is that it has been estimated that the deposition of airborne nitrogen on the lake accounts for about 30% of the total load. The load from agricultural activities, on the other hand has reduced to about 35% between 1985 and 1995.

Figure 4.6 Region of Göta Älv - Klarälven : sources of anthropogenic N load (in %)

30

35 35

Agriculture Urban Waste Water Deposition

Source: Swedish EPA

As can be seen in the above figure, agriculture creates a significant pressure and should be prioritised (together with urban waste water) in the regional pollution abatement work and obviously measures should be targeted at areas with leaching-prone soils (ie. mainly south of Lake Vänern).

Lake Vättern Region

This large area drains to the Bråviken which shows eutrophication symptoms and has already been designated as an NVZ under Directive 91/676/EEC. It is reported that the inner parts of the area are characterised by a significant retention potential. Agriculture is the largest source of nitrogen (about 45% of the total load) in this region. The two other major sources are deposition (estimated at about 30%) and waste water (contribution not estimated). However, retention in these agricultural areas is relatively low (especially in the areas with light soils and with a high proportion of grain cultivation) which means that a significant proportion of the N is reaching the sea which, despite a relatively high water turnover, suffers from eutrophication effects. Therefore, the area should be given priority for pollution abatement measures.

Lake Mälaren Region

This area is characterised by high nitrogen discharges which vary widely along the coastal section (which has already been designated as an NVZ). In the Himmerfjärden, the Nyköping district and the Stockholm archipelago, N discharges are high and water turnover generally low. This results in eutrophic conditions, as already recognised. As shown below, the main

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 38 sources of nitrogen are waste water treatment plants (60%) with agriculture accounting for about 20% and deposition 10% of total discharges.

Figure 4.7 Region of Lake Mälaren - source of anthropogenic N load (in %)

10

20

60

Agriculture Urban waste water Deposition

Source: Swedish EPA

This region is also characterised by a large population and relatively intensive agriculture which results in very heavy loads. However, it is reported that emissions from agriculture have been reduced by 45% in the area, largely due to the fact that a large portion of arable land has been taken out of production. Such a situation, however, could easily be reversed which means that the threat posed by agricultural activities on water quality in the region has not disappeared but only momentarily reduced. Retention is low in the agricultural areas and nutrient reduction measures should be prioritised in this region.

4.2 LAKE QUALITY - ASSESSMENT

4.2.1 Introduction

The following subsections are based on data provided by the SGU and which included measurements of:

• (NO2+NO3)-N; • Total N; • TOC; • Oxygen concentration; • Chlorophyll-a (where available)

It can be noticed that phosphorous has not been included in the factors assessed. It is mainly due to the fact that P is considered as the limiting factor and that other factors have largely been ignored. For this reason the assessment summarised in the following sections focuses on other factors

such as N and O2.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 39 Table 4.3 Quality Criteria

Categories Parameters Good Fair Bad Very bad Bloom indicator Chlorophyll-a (µg/l) 2-4 4-8 8-20 >20

Nutrient Total nitrogen (µg/l) 300-400 400-600 600-1200 >1200

Organic matter TOC (mg C/l) 2.5-3.5 3.5-6.5 6.5-15 >15

Oxygen (mg O2/l) 6.4-9 4-6.4 2-4 <2

Source: Swedish EPA

For each lake reviewed, the monitoring results are summarised for (1) the lake itself and (2) the lake’s tributaries. Similarly, the maps for each lake show the monitoring stations (in red) both within the lake (left) and on the tributaries (right). It has to be noted that the maps do not indicate the drainage basins of the lakes themselves but are rather a regional map showing the location of the monitoring stations.

4.2.2 Lake Vättern

Introduction

The basin of this lake is boat shaped and is easily affected by wind and atmospheric pressure variations. Strong currents affect sedimentation and the distribution of erosion, accumulation and transportational bottoms in lake Vättern is reflected in the concentration of metals in the bottom. The lake is characterised by its depth, transparency and relatively large volume. The drainage/lake area ratio is 2.3 which suggests a low areal loading and hence generally oligotrophic status. There are six large and sixteen smaller tributaries to the lake and many small brooks.

Figure 4.7 shows the location of the monitoring stations in both the lakes and tributaries. It must be mentioned that the area shown is not the drainage area of the lake itself but rather a regional drainage area (‘amalgamation’ of main drainage basins, as defined by the EPA).

Monitoring Results

(a) the lake

The results from the monitoring carried out in the lake show relatively oligotrophic conditions. Indeed, for all monitoring stations:

• the NO2+NO3-N values range between 400-500 µg/l; • The TOC measurements range between 2.5-5 mg/l with a marked decreasing trend between 1997 and 2000; • the oxygen content remains well above 10 mg/l at all stations. There is no indication however, whether these concentrations are found during

daytime or at night (during which O2 concentrations are expected to be lower than in daytime).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 40 However, given that background concentrations for total N range between 300-400 µgN/l, those found in the lake are relatively high at all stations and vary between 600-800 µgN/l.

Figure 4.8 Lake Vättern - Monitoring Stations

Source: SGU

(b) the Tributaries

The monitoring carried out in the rivers flowing into the lake shows quite

different results. Indeed, NO2+NO3-N concentrations reached over 5,000 µg/l in 1998, down to 3,000 µg/l in 1999 at the Malmabäcken monitoring station and just below 1,000 µg/l at the Munksjön station (both located in the Jönköpings län district). Although there is a clear downward trend, these are still high values. At the same stations, the opposite trend is observed for TOC measurements. Indeed, at the Malmabäcken monitoring station for example, TOC concentration went from about 7.5 mg/l in 1997 to about 15 mg/l in 1999. This suggests that nutrient enrichment is occurring at these stations. It is difficult to identify with certainty the source as there are both urban (Huskvarna and Jönköping) and agricultural areas in that region and in the vicinity of the lake.

The monitoring results for two stations located on the tributaries in the

Östergötland district also show high NO2+NO3-N concentrations with peaks of just below 5,000 µg/l in 1998 at the Mjölnaån monitoring station. The results for 1999 are still in the region of 2,000 µg/l. This is also accompanied by high TOC concentrations (15-20 mg/l) with peaks up to 30 mg/l in 1999.

Results for total N also show very high concentrations at most stations around the lake. Indeed concentrations of up to 5,000 µgN/l (even over 15,000 µgN/l in the mid-1990’s) are encountered at several monitoring stations.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 41 CONCLUSION

Although there is limited information about the eutrophic status of Lake Vättern (eg. biomonitoring, algal blooms, etc), the results from the chemical monitoring summarised above show that conditions (high total N

concentrations within the lake and high total N, NO2+NO3-N and TOC concentration in the catchment area) are favourable for the development of eutrophic conditions.

Furthermore, a significant proportion of the area east of lake Vättern is drained to the Bråviken which has already been designated as an NVZ under the Directive. Figure 2.3 clearly shows that agriculture is the main activity in that area which has also been identified as eutrophic by the Swedish EPA (Figure 2.5) and its impact on the trophic status of the Bråviken must be considerable.

This gives several indications that the area on the eastern side of Lake Vättern where agriculture is the main activity does qualify for designation under the Nitrates Directive.

4.2.3 Lake Vänern

Introduction

Lake Vänern is the largest lake in Sweden and the fourth largest lake in Europe. There are more than one hundred tributaries, the main one flowing into the northern part. Lake Vänern drains into the Kattegat (the Atlantic) via the Gota River and the drainage area of these two bodies covers 10% of the total area of Sweden. It is situated in a region where deposits in the drainage area mainly consist of moraines poor in nutrients. A rift zone of north-south extension divides the lake into two major basins, Varmlandssjon and Dalbosjon. The good level of water exchange between the archipelago zone and the open water is, however, decisive for the generally extensive spreading of pollutants.

The main problems associated with water quality in the lake have historically been due to outlets from pulp mills mainly located on the northern shore of Varmlandssjon. Effluents from these industries contain high concentrations of organic material with lignin components and contribute to the brownish colour of the water.

Twice a year, in spring and autumn, the water masses are totally mixed, but in the summer a thermocline is established. In the spring the heating of water is fastest in the shallow areas and therefore a zone with warmer water appears around the margins of the lake. This thermal bar temporarily retards the water exchange between the coastal zone and the open lake, resulting in an obvious quality difference between these two areas.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 42 Monitoring Results

(a) The lake

The results from the monitoring carried out in the lake show relatively oligotrophic conditions. Indeed, for all monitoring stations:

• the NO2+NO3-N values range between 500-600 µg/l. Peaks, however, are observed at Mariestadsviken (1) during the months of May-June; • The TOC measurements range between 4-6 mg/l with, here again, peaks to 8 mg/l at the station of Mariestadsviken during the months of May-June; • the oxygen content remains well above 10 mg/l at all stations.

Figure 4.9 Lake Vänern - Monitoring stations

Source: SGU

As for Lake Vättern, total-N concentrations are relatively high. Concentrations above 650 µg/l are frequently measured at all monitoring stations on the lake (with peak at >1,500 µg N/l at certain stations). The results show that total-N concentrations were rising until the early 1990’s and have been relatively stable since then at a level fluctuating around 800 µg N/l which corresponds to between two or three times the “normal” background level in Sweden. According to the Lake Vänern Society for Water Conservation, the nitrogen levels in the lake today are higher than they were in the 1970s, and need to be

(1) The monitoring station of Mariestadsviken is located on the south shores of the lake, the drainage area of which is an area of intensive agricultural activities (Västergötland).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 43 reduced. “The most important ways of achieving this are to take measures in the agricultural sector to reduce leakage of nitrogen into the lake”. It also mentions that although P levels are much closer to background levels, certain bays suffer from high P levels as well as from high N levels (throughout the lake in the case of N). More particularly it is specified that N outflow through the river Göta must be reduced as overfertilisation is significant on the West coast.

(b) Tributaries

With regard to the tributaries, high NO2+NO3-N concentrations have been observed at several locations: Dalbergsån, Mariestad, Lidköping and Nossan Sal, all of which are located in Västergötland. Similarly, high TOC concentrations were found in these areas. The same monitoring stations also show very high total-N concentrations with peaks up to 5,000 µg N/l and constant concentrations above 2,000 µg N/l during 1999.

CONCLUSION

Although there is limited information about the eutrophic status of Lake Vänern (eg. biomonitoring, algal blooms, etc), the results from the chemical monitoring summarised above show that conditions (high total N

concentrations within the lake and high total N, NO2+NO3-N and TOC concentration in the catchment area) are favourable for the development of eutrophic conditions and that nitrogen levels are too high.

Furthermore, Figure 2.3 clearly shows that agriculture is a significant activity in areas around the lake as well as along the Gota river which drains to the Kattegat (which has also been identified as a Vulnerable Zone). Figure 2.5 also shows that the agricultural areas around Lake Vänern have been identified as eutrophic by the Swedish EPA.

Therefore, there are indications that the areas located in agricultural intensive regions (ie. Västergötland) do fall under the requirements of Directive 91/676/EEC and do qualify for designation as NVZ.

4.2.4 Lake Hjälmaren

Introduction

Lake Hjälmaren is situated in a region with Archaean rocks where the deposits around the lake are dominated by lime-rich clays which makes these areas well suited for cultivation. Large agricultural areas surrounding the lake contribute to the nutrient loading of the water. This lake is shallow and of eutrophic character (1) . It consists of four main basins, separated from each other by islands and narrow sounds. The lake is used as a freshwater reservoir and for recreational purposes. The accelerated eutrophication during the last

(1) Http:/www.ilec.or.jp

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 44 thirty years has especially affected the two basins closest to the town of Orebro due to the increased population of the town.

Figure 4.10 Lake Hjälmaren - Monitoring stations

Source: SLU

Monitoring results

Unfortunately, very little information is available on Lake Hjälmaren. The available monitoring results for the period 1990-1996 (only one monitoring

point in the middle of the lake) indicate relatively low NO2+NO3-N concentrations and good oxygen conditions. Total-N concentrations vary between 600-900 µg N/l. Chlorophyll-a concentrations, however are relatively high, with a peak to 17.5 mg/m3 in 1995 (measurements for subsequent years are not available).

High NO2+NO3-N concentrations have been measured in the tributaries of the lake and these are accompanied by low oxygen concentrations (just above 5 mg/l) during the summer period. Although not available for all stations, total-N concentrations are very high (up to 4,000 µg N/l) for several stations.

CONCLUSION

As for other lakes in Sweden, the results from the chemical monitoring summarised above show that the catchment area of the lake is characterised by conditions which are favourable for the development of eutrophic conditions and nitrogen concentrations which are much higher than the background concentration for the region.

Figure 2.3 shows that Lake Hjälmaren is surrounded by agricultural areas and that the whole region has been identified as eutrophic by the Swedish EPA. This clearly suggests that the agricultural areas around Lake Hjälmaren do fall under Directive 91/676/EEC and do qualify for designation as an NVZ.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 45 4.2.5 Lake Mälaren

Introduction

Lake Mälaren is situated in a region with Archaean rocks where deposits around the lake, especially its north-eastern and southern parts, are dominated by lime-rich clays which make these areas well suited for cultivation. Central Sweden is a highly cultivated area where the use of inorganic fertilizers contributes to the nutrient loading on the lakes.

Lake Mälaren is a very complicated system of waters composed of bays with different characteristic. On the basis of its topography the lake can be divided into five basins each with its own chemical and biological status. The quotient between drainage area and lake surface is about 20 which indicates a large surrounding area contributing to the loading on the lake. Lake Mälaren has become more eutrophic during the last 30 to 40 years and this may be of concern as Lake Mälaren is becoming an important source of freshwater. Stockholm is situated at the outlet of Lake Mälaren into the Baltic.

Seventy-five percent of the inflow to Lake Mälaren enters the western part of the lake but the inflow into the north-eastern area is also important. This means that the water flows mainly in two directions, from west to east and from north-east to south before entering the connection with the Baltic. As shown in Figure 2.3, the areas north and west of the lake are agricultural areas.

Monitoring Results

(a) The Lake

High NO2+NO3-N concentrations are encountered in four different parts of the lake: Västeråsfjärden, Svinnengarnsviken, Skarven and Ekoln Vreta Udd. High TOC concentrations are also observed at all locations (> 6.5 mg/l). Furthermore, low oxygen concentrations are encountered at several locations (usually during the period March - July).

Figure 4.11 Lake Mälaren - Monitoring stations

Source: SGU Total-N concentrations are also high (varying between 600 and 4,000 µg N/l) and the measurements show a general increasing trend throughout the 1990’s.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 46 Such levels are much higher than the background concentration for the region. The highest concentrations are, as for TOC, measured during the May-August period. In relation to Chlorphyll-a, concentration above 10 mg/m3 have been observed at most monitoring stations throughout the 1990’s with peaks occurring during the summer period and concentrations of up to 50 mg/m3 being recorded.

(b) Tributaries

The monitoring results obtained for the tributaries of Lake Mälaren also show similar situations of high NO2+NO3-N and TOC concentrations. Total-N concentrations are also consistently high with concentrations up to 5,000 µg N/l.

These results suggest that eutrophic conditions are prevalent within the lake as well as in it’s drainage area. This situation may be due both to urban areas (eg. Västerås, Upssala, etc) and agricultural areas. As can be seen on Figure 2.1, the area North and West of the Lake are important agricultural areas which are very likely to contribute to the trophic condition of the lake.

CONCLUSION

Those results from the chemical monitoring summarised above show that conditions (high total N concentrations within the lake and high total N,

NO2+NO3-N and TOC concentration in the catchment area) are favourable for the development of eutrophic conditions and that the lake itself does contribute to the eutrophication of the coastal waters of the Baltic (which has been identified as an NVZ).

Intensive agriculture, as shown in Figure 2.3 (significant grain cultivation) is taking place on the western and northern parts of the lake’s drainage area (which are characterised by light soils of low retention).

Those results suggest that the lake and the western and northern catchment areas do fall under Directive 91/676/EEC and do qualify for designation as an NVZ.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 47 5 CONCLUSIONS

5.1 EUTROPHICATION IN SWEDEN

Eutrophication is widely acknowledged as one of Sweden’s most widespread environmental problems which occurs in both freshwaters and marine/coastal waters. In relation to marine and coastal waters, large parts of the Baltic and the Kattegat are suffering from severe oxygen deficiency and related eutrophication and this was reflected in Sweden’s first round of designations.

In relation to freshwaters, it is estimated that over 14,000 of Sweden’s 96,000 lakes show elevated concentrations of phosphorus and 20,000 of them show elevated concentrations of nitrogen. Large areas near Lake Vänern, Lake Vättern, Lake Mälaren and Lake Hjälmaren were identified by the Swedish EPA as regions with eutrophic water bodies.

The available information seems to indicate that, so far, the identification of Vulnerable Zones very much focuses on the eutrophic waters of the Baltic. Only 1 freshwater lakes was designated and this seems to have been done on

the basis of it’s high NO3 concentration (> 50 mg/l) and related eutrophic conditions. The current designation does not seem to reflect the eutrophication problems encountered in the intensive agriculture areas around Lake Vänern (Västergötland), Lake Mälaren and Lake Hjälmaren as well as the intensive agricultural areas of northern Östergötland which are all characterised by high nitrogen concentrations when compared to background levels (and in some cases, with P concentrations close to background level).

The main reason for this appears to be that P is considered as the limiting factor. However, phosphorous has accumulated in both soil and water for a number of years and is steadily released to surface waters. The phosphorous trapped in sediment is leached in large amounts when oxygen concentrations are reduced to low levels and if any movement of the water mass transports the dissolved P to the upper layer, secondary eutrophication will occur. As the accumulation of P in the sediment in Sweden appears to be significant (excessive), it seems that P can not be a ‘limiting’ or a ‘management’ factor anymore. On the contrary, such excesses of phosphorous in freshwater lakes usually implies that these become limited by nitrogen. Furthermore, and as detailed in Section 2 of the report, there are good indications that both the causes of eutrophication and degree of productivity are very likely to be due to both phosphorous and nitrogen and that both factors must be taken into consideration in order to control it.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 48 5.2 SUGGESTED ADDITIONAL VULNERABLE ZONES

As shown in the report, Lake Vänern, Lake Vättern, Lake Mälaren and Lake Hjälmaren have been identified as eutrophic and are characterised by high nitrate concentrations (when compared to the low background value typical of pristine waters in that region). This therefore suggests that these waters can be considered as threatened by N eutrophication and since a large proportion of the land in these areas is used for intensive agriculture, high N losses originate from agriculture (see Figure 4.5). These therefore qualify for designation under the Nitrates Directive.

This is accompanied by the fact that a high proportion of aquifers in those regions have relatively high N concentrations (≥ class 3).

Table 5.1 Suggested Additional Vulnerable Zones

Water Body Suggested Designated Area Lake Vänern (and tributaries) Agricultural areas in Västergötland (South), west of the lake (Göta river area) and Värmlandnäs

Lake Vättern (and tributaries) Agricultural area east of lake Vättern (Östergötland)

Lakes Hjälmaren and Mälaren Agricultural areas around the two lakes

This is illustrated on the Map in Annex C of this report. Note that this map is only intended to provide an estimation of the size of the problem areas and suggested NVZ boundaries.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 49