LAKE HJALMAREN

A view of the lakeshore in Country of Orebro

Photo.
Photo: B. Wiksell




A. LOCATION

  • Orebro, Vastmanlands and Sodermanlands, Sweden.
  • 59:08-59:18N, 15:13-16:19E; 22.0 m above sea level.


B. DESCRIPTION

    Lake Hjalmaren is situated in a region with Archaean rocks. 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.
    Lake Hjalmaren is shallow and of eutrophic character. It consists of four main basins, separated from each other by islands and narrow sounds. The lake is used as a freshwater reservoir, as a recipient of sewage water-mainly from the town Orebro in the westernmost part - and for recreational purposes. The accelerated eutrophication during the last thirty years has especially affected the two basins closest to the town Orebro due to the increased population of the town. The main inflow runs via the town of Orebro to the westernmost basin. Lake Hjalmaren drains via the outlet in the easternmost part to Lake Malaren.
    An eighteenth-century observer noted that the water of Lake Hjalmaren was transparent and had a good taste but got thicker during the heavy gales that frequently occurred. The thick water included many nutrients and seemed to be good for the fishes, as they were generally well-fed. Water blooms were common and lasted from mid-June to late autumn (Uggla Hillebrandsson, 1786).


C. PHYSICAL DIMENSIONS (Q, 2)

    Surface area [km2] 478
    Volume [km3] 2.9
    Maximum depth [m] 22
    Mean depth [m] 6.1
    Water level Regulated
    Length of shoreline [km] 428
    Residence time [yr] 3.3*
    Catchment area [km2] 3,575
    * 1981-1985.


D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL (Q)

  • Bathymetric map: Fig. EUR-14-01.
  • Names of main islands: Vinon (5 km2).
  • Number of outflowing rivers and channels (name)
    2 (Hyndevadsstom R. and Hjalmare Canal).

D2 CLIMATIC

  • Climatic data at Stockholm, 1931-1960 (Q)

    Mean temp. [deg C]
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    -2.9 -3.1 -0.7 4.4 10.1 14.9 17.8 16.6 12.2 7.1 2.8 0.1 6.6
    Precipitation [mm]
    43 30 26 31 34 45 61 76 60 48 53 48 555
  • Number of hours of bright sunshine: 1,800-2,000 hr yr-1 (3).
  • Solar radiation: 8.9 MJ m-2 day-1.

    Fig. EUR-14-01
    Bathymetric map [m].


  • Water temperature [deg C](Q)

    Storhjalmaren, 1981-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - 0.5 - 6.5 14.5 19.0 18.4 14.2 9.7 - -
    5 - - 0.8 - 6.8 15.0 18.3 19.1 14.9 9.8 - -
    10 - - 1.6 - 6.6 14.7 18.1 19.0 14.9 9.6 - -
    15 - - 2.4 - 6.6 14.6 17.9 18.2 14.9 9.6 - -
  • Freezing period (1984-1985): 139 days (3).
  • Notes on water mixing and thermocline formation: Not stratifying (3).


E. LAKE WATER QUALITY

E1 TRANSPARENCY [m](Q)

    Storhjalmaren, 1981-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    - - 3.5 - 1.5 2.6 3.0 3.3 2.1 2.3 - -

E2 pH (Q)

    Storhjalmaren, 1981-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - 7.5 - 7.6 7.6 7.6 7.5 7.7 7.7 - -
    5 - - 7.6 - 7.8 7.5 7.6 7.6 7.7 7.7 - -
    10 - - 7.3 - 7.8 7.6 7.5 7.7 7.8 7.5 - -
    15 - - 7.2 - 7.7 7.6 7.6 7.4 7.6 7.7 - -

E4 DO [mg l-1](Q)

    Storhjalmaren, 1981-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - 13.3 - 12.3 9.2 8.2 8.4 8.9 9.8 - -
    5 - - 13.1 - 12.8 8.2 8.0 8.0 9.0 10.4 - -
    10 - - 9.4 - 13.4 8.6 8.2 8.2 9.0 10.4 - -
    15 - - 7.5 - 13.1 8.2 7.8 6.7 8.5 10.4 - -

E5 COD [mg l-1](Q) Determined by KMnO4 method.

    Storhjalmaren, 1981-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - 25.8 - 30.5 28.0 27.7 27.5 27.4 24.9 - -
    5 - - 24.4 - 23.6 24.5 38.1 23.7 25.9 21.5 - -
    10 - - 25.1 - 24.1 23.7 39.6 24.1 26.6 20.9 - -
    15 - - 25.2 - 23.8 23.8 38.5 23.1 26.4 22.4 - -

E6 CHLOROPHYLL CONCENTRATION [micro l-1](Q)

    Storhjalmaren, 1981-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - 2.2 - 19.3 7.7 7.5 12.1 18.4 11.2 - -
    5 - - 2.2 - 17.5 5.9 4.7 7.7 19.9 12.6 - -
    10 - - 2.2 - 16.0 5.1 3.9 7.3 18.8 13.4 - -
    15 - - 2.1 - 15.6 4.8 3.4 4.5 17.2 13.7 - -

E7 NITROGEN CONCENTRATION (Q)

  • Total-N [mg l-1]

    Storhjalmaren, 1981-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - 0.834 - 1.008 0.874 0.719 0.628 0.721 0.621 - -
    5 - - 0.742 - 0.883 0.700 0.625 0.568 0.757 0.553 - -
    10 - - 0.849 - 1.011 0.612 0.566 0.587 0.798 0.525 - -
    15 - - 0.830 - 0.922 0.715 0.545 0.609 0.804 0.675 - -

E8 PHOSPHORUS CONCENTRATION (Q)

  • Total-P [mg l-1]

    Storhjalmaren, 1981-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - 0.042 - 0.038 0.035 0.039 0.047 0.072 0.062 - -
    5 - - 0.041 - 0.033 0.021 0.040 0.021 0.063 0.046 - -
    10 - - 0.046 - 0.025 0.029 0.036 0.021 0.076 0.056 - -
    15 - - 0.049 - 0.025 0.032 0.039 0.032 0.080 0.053 - -

E10 PAST TRENDS (1): Fig. EUR-14-02, 03 and 04.

    Fig. EUR-14-02
    Concentration of chlorophyll a in various basins during the period from 1966 to 1973 (growth season mean value)[micro l-1].


    Fig. EUR-14-03
    Concentration of Total-N in various basins during the period from 1966 to 1973 (growth season mean value)[mg l-1].


    Fig. EUR-14-04
    Concentration of Total-P in various basins during the period from 1966 to 1973 (growth season mean value)[mg l-1].



F. BIOLOGICAL FEATURES

F1 FLORA

  • Emerged macrophytes: Phragmites australis (4).
  • Floating macrophytes: Nuphar luteum (4).
  • Phytoplankton (Q)
    Actinocyclus normanii f. subsalsa, Melosira islandica, M. granulata, Stephanodiscus rotula, S. hantzchii v. pusillus, Microcystis aeruginosa, Asterionella formosa, Rhodomonas lacustris, Ceratium hirundinella, Gomphosphaeria naegeliana.

F2 FAUNA

  • Zooplankton (Q)
    Copepoda (Cyclopidae spp., Eudiaptomus gracilis), Cladocera (Chydorus sphaericus, Daphnia cucullata), Rotatoria (Keratella cochlearis, K. quadrata, Kellicottia longispina).
  • Benthos (Q)
    Diptera (Chironomus plumosus, Procladius spp.), Oligochaeta (Potamothrix hammoniensis, Limnodrilus hoffmeisteri), Bivalvia (Pisidium casertanum).
  • Fish (5)
    Lucioperca lucioperca*, Esox lucius*, Anguilla anguilla*, Perca fluviatilis*. * Economically important.

F3 PRIMARY PRODUCTION RATE [g C m-2 yr-1](Q)

  • Gross production
    Station Storhjalmaren, 1972: 170.

F4 BIOMASS: Fig. EUR-14-05 (1).

    Fig. EUR-14-05
    a: Seasonal dynamics of phytoplankton in hypereutrophic basin H, 1972. b: Seasonal dynamics of phytoplankton in moderately eutrophic basin S, 1972 [mm3 l-1].


F5 FISHERY PRODUCTS (Q)

  • Annual fish catch [metric tons] 1986: 180.

F6 PAST TRENDS: Fig. EUR-14-06, 07 and 08.

    Fig. EUR-14-06
    Past trend of phytoplankton in various basins during the period from 1966 to 1973 (growth season mean values)[mm3 l-1](1).


    Fig. EUR-14-07
    Phytoplankton volumes in relation to nutrient loading in different basins (growth season mean values, 1966-1973)[mm3 l-1](1).


    Fig. EUR-14-08
    Past trend of annual fish catch [metric tons](Q).



G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA (8, 6)

    Area [km2] [%]
    Natural landscape Woody vegetation 1,677 51.9
    Agricultural land 821 25.4
    Others 733 22.7
    Total 3,231 100.0
  • Main types of woody vegetation: Spruce, pine and deciduous forest.
  • Main kinds of crops: Wheat, rye and barley.
  • Levels of fertilizer application on crop fields: Moderate.

G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE (7)

    1981
    No. of persons engaged No. of establishments
    - Secondry industry
    Mines and manufacturing industry 26,095 309
    Food stuffs 2,559 25
    Textile 683 20
    Wood 812 18
    Pulp and paper 2,602 37
    Chemical 592 17
    Soil and stone 967 17
    Metal products 2,117 12
    Workshop 15,228 149
    - Others 315 5
  • Numbers of domestic animals in the catchment area
    Cattle 35,400, sheep 7,300, swine 36,600, poultry 121,600.

G3 POPULATION IN THE CATCHMENT AREA (7)

    1980
    Population Population density [km-2] Major cities (population)
    Total 242,200 67.7 Orebro


H. LAKE UTILIZATION

H1 LAKE UTILIZATION (Q)

    Source of water, navigation and transportation, sightseeing and tourism, recreation (swimming, sport-fishing, yachting) and fisheries.

H2 THE LAKE AS WATER RESOURCE (Q)

    About 1985
    Use rate [m3 sec-1]
    Domestic 0.049


I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS

I1 ENHANCED SILTATION (Q)

  • Extent of damage: Not serious.

I2 TOXIC CONTAMINATION

  • Present status: Detected but not serious (Q).
  • Main contaminants, their concentrations and sources (9, 10, 11)

    Concentration [ppm]
    Bottom mud (dry wt.) (before 1977) Fish*1 (wet wt.) (1976) Fish*2 (wet wt.) (1985)
    Hg 0.3 - -
    Cu 50 - -
    Ni 70 - -
    Pb 100 - -
    Zn 153 - -
    Cr 70 - -
    Total Hg - - 0.3
    DDE+DDT+DDD - 0.41 -
    PCBs - 2.6 -
    *1 Liver of burbot at Vinon.
    *2 Muscle of pike at several stations.
  • Food safety standards or tolerance limits for toxic contaminant residue (11)
    For Hg in fish: 1 ppm. For DDE+DDT+DDD in fish: 5 ppm. For PCBs in liter of fish: 5 ppm. For Cs137 in freshwater fish: 1500 Bq (1 Ci= 3.7x1.0E+10 Bq).
  • Supplementary notes
    Number of Bq of Cs137 per kg muscle (wet wt.) of pike perch caught in 1986 was 18.

I3 EUTROPHICATION

  • Nuisance caused by eutrophication (Q)
    Unusual algal bloom: Microcystis aeruginosa, Gomphosphaeria naegeliana. Foul smell of tap water: Synura petersenii. Fouling of gill net: Melosira spp.
  • Nitrogen and phosphorus loadings to the lake [t yr-1](6)

    1981-1985

    Sources

    		 Total
    T-N 2,750
    T-P 65

I4 ACIDIFICATION (Q)

  • Extent of damage: None.


J. WASTEWATER TREATMENTS (Q)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA

    f) Extensive development of the catchment area with provision for municipal wastewater treatment.

J2 APPROXIMATE PERCENTAGE DISTRIBUTION OF POLLUTANT LOADS

    1981-1985
    N [%] P [%]
    Natural background from ground 18 24
    Atmospheric deposition 10 4
    Municipal and industrial sources 11 19
    Cultured fields minus background 57 49
    Other fields minus background 4 4
    Total 100 100

J3 SANITARY FACILITIES AND SEWERAGE

  • Percentage of municipal population in the catchment area provided with
    adequate sanitary facilities (on.site treatment systems) or public sewerage: 100%.
  • Percentage of rural population with adequate sanitary facilities (on-site
    treatment systems): >90%.


K. IMPROVEMENT WORKS IN THE LAKE (Q)

K1 RESTORATION

    Weed cutting in small areas.


M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M1 NATIONAL AND LOCAL LAWS CONCERNED (12)

  • Names of the laws (the year of legislation)
    1. The Nature Conservation Act (1964)
    2. The Nature Conservation Ordinance (1976)
    3. The Environment Protection Act (1969)
    4. The Environment Protection Ordinance (1981)
    5. The Act on Chemical Product (1985)
    6. The Ordinance on Chemical Products (1985)
    7. The Ordinance Relating to Hazardous Waste (1985)
    8. The Ordinance on Pesticides (1985)
    9. The Ordinance on Certain Products Hazardous to Health and to the Environment (1985)
    10. The Ordinance on PCB etc (1985)
    11. The Marine Dumping Prohibition Act (1971)
    12. The Dumping Ordinance (1971)
    13. The Act on Measures against Water Pollution from Vessels (1980)
    14. The Ordinance on Measures against Water Pollution from Vessels (1980)
    15. The Act on Sulphur Content in Fuel Oil (1976)
    16. The Ordinance on Sulphur Content in Fuel Oil (1976)
    17. The Ordinance on State Grants for the Liming of Lakes and Watercourses (1982)
    18. The Standing Instructions to the National Swedish Environmental Protection Board (1967)
    19. The Standing Instructions to the National Franchise Board for Environment Protection (1969)
    20. The Environment Protection Statutes enacted by the National Swedish Environmental Protection Board are published as from 1977 in the Code of Statutes of the National Swedish Environmental Protection Board, SNFS
    21. The Health Protection Act (1982)
    22. The Health Protection Ordinance (1983)
    23. The Water Act (1983)
    24. The Water Association Act (1976)
    25. The Act on Transport of Dangerous Goods (1982)
    26. The Ordinance on Transport of Dangerous Goods (1982)
    27. The Act on Fishing Rights (1950)
    28. The Fisheries Ordinance (1982)
    29. The Planning and Building Act (1987)
    30. The National Resources Act (1987)

M2 INSTITUTIONAL MEASURES (Q)

  1. Water Quality Monitoring of Lake Hjalmaren by the Environment Quality Laboratory of the National Swedish Environmental Protection Board, The monitoring program started in 1978, but some stations had been investigated since 1966.
  2. The County Administrations and the National Swedish Environment Protection Board are responsible for control and restoration.


N. SOURCES OF DATA

  1. Questionnaire filled by Drs. T. Ahl, B. Karlsson, L. Marelius, H. Olsson, G. Persson, A. Tolstoy, T. Wiederholm and E. Willen, the Environment Quality Laboratory at the National Swedish Environmental Protection Board, Stockholm, Sweden.
  2. Willen, E. (1984) The large lakes of Sweden: Vanern, Vattern, Malaren and Hjalmaren. "Ecosystems of the World 23, Lakes and Reservoirs" (ed. Taub, F. B.), pp. 107-134. Elsevier, Amsterdam-Oxford-New York-Tokyo.
  3. Hakansson, L., Karlsson, B. & Eriksson, s. (1983) Geomorfologiskt sjoregister over Sverige. The National Swedish Environmental Protection Board, SNV PM 1650.
  4. The Swedish Meteorological and Hydrological Institute (1987) Miljostatistisk arsbok 1986-1987. Naturmiljon i siffror.-Arlov. 224 pp.
  5. Andersson, B. & Eriksson, S. (1974) Hogre vattengetation i Hjalmaren. The National Swedish Environmental Protection Board, SNV PM 461, pp. 1-56.
  6. Information obtained from the Commission of Fishery in the County of Vastmanland.
  7. Olsson, H. (1987) Hjalmarens fosfor-och kvavelastning 1966-1985. The National Swedish Environmental Protection Board, SNV Rapport 3309, 47 pp.
  8. The Swedish Meteorological and Hydrological Institute (1985) Statistik pa avrinningsomraden 1980-1981. Befolkning, jordruk och industri.-Na 11 SM 8501.-Stockholm. 92 pp.
  9. Information obtained from the County of Orebro.
  10. Hakansson, L. (1977) Sediments as Indicators of Contamination. Investigations in the Four Largest Swedish Lakes. The National Swedish Environmental Protection Board, SNV PM 839, 159 pp.
  11. Andersson, O., Linder, C. E. & Vaz, R. (1984) Levels of organochlorine pesticides, PCBs and certain other organohalogen compounds in fishery products in Sweden, 1976-1982. Var Foda, 36: 1-59 The National Food Administration.
  12. Results obtained from the National Food Administration, Sweden.
  13. Names and years of national and local laws obtained from L. Karlstrom, the National Swedish Environmental Protection Board.