LAKE STECHLIN

A view on the lake

Photo.
Photo: W. Scheffler


A. LOCATION

  • Potsdam, East Germany.*
  • 53:10N, 13:02E; 59.7 m above sea level.
    * Place names are not updated.

B. DESCRIPTION

    Lake Stechlin with its large number of bights was formed by deep melting of dead ice blocks and erosion of melt water channels after the Weichselian stage of the last glaciation. It is situated in the outwash plain immediately to the south of the terminal moraine of the Furstenberger Staffel. Formations of gravel and sand deposits reaching heights up to 84.5 m above the sea level and approaching the shores are towards the northeast of the lake.
    Lake Stechlin has an area of 4.3 km2, a maximum depth of 68 m, and is stratified in summer with small hypolimnetic oxygen depletion. Towards the west and southwest, a sand plain follows at heights of 70-80 m above the sea level bordered on the east by a ground moraine. Before 1750, surface in- or effluents were virtually absent. The natural real surface catchment area amounts to 12.4 km2 of which 80% are covered by forests. The actual sub-surf ace catchment area amounts 26.0 km2. The actual water level is 59.7 m above the sea level. Before 1750, it was 60.7 m.
    The lake is locally cut deeply into its environs with considerably steep shores on the northwest and northeast sides of the north bay. The Fenchelberg, the highest point (84.5 m a.s.l.) of the Lake Stechlin area, is situated immediately on its northeast shore.
    The lake is divided in four basins or bays: the north basin with the maximum depth of the whole lake (68 m); the relatively shallow central basin, 59 m deep; the west basin influenced directly by the cooling water circuit, 41 m deep and separated from the south basin (35 m) by a nearly 1.2 km long peninsula stretching from west to east. During the stagnation phases the hypolimnion of the different basins is not changeable mutually. The volumes of the four basins are: west basin 19,000,000 m3, north basin 37,000,000 m3, south basin 13,000,000 m3, central basin 28,000,000 m3.
    The shore of Like Stechlin is bounded by a more or less closed large zone of mixed forests mainly consisting of pines, beeches, willows and alders. Allochthonous input of organic matter - mostly leaves, twigs, pollen and fruits from the surrounding trees - are potentially significant for material balance and production in the lake. Open land borders on the shores up to 4.8% only and the trophic level of the lake water is still oligotrophic. Now the input of cooling water circuit from a nuclear power plant and the man-made surface run-in of water from Lake Dagow influence mainly the ecosystem (1).

C. PHYSICAL DIMENSIONS (1)

    Surface area [km2] 4
    Volume [km3] 0.0969
    Maximum depth [m] 68
    Mean depth [m] 22.8
    Water level Regulated
    Length of shoreline [km] 16.1
    Catchment area [km2] 26

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL
  • Sketch map: Fig. EUR-31-01.
  • Bathymetric map: Fig. EUR-31-02.
  • Names of main islands: None (1).
  • Number of outflowing rivers and channels (name): 1 (Polzow Canal)(2).
D2 CLIMATIC
  • Climatic data at Neuglobsow
    Mean temp. [deg C]*1
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    -0.9 -0.5 2.4 6.7 12.1 15.6 17.3 16.2 12.7 8.2 3.6 0.6 7.9
    Precipitation [mm]*2
    41 32 34 45 58 60 76 57 45 41 51 53 593
    *1 1901-1980 (3). *2 1958-1981 (4).
  • Solar radiation (1967-1976): 9.6 MJ m-2 day-1 (5).

    Fig. EUR-31-01
    Sketch map of the lake and its catchment area (1).

    Fig. EUR-31-02
    Bathymetric map [m](1).

  • Water temperature [deg C](6)
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 2.8 1.9 2.4 5.0 10.4 16.9 18.7 18.8 16.9 12.8 8.5 5.0
    6 3.2 2.3 2.6 4.6 9.2 14.2 17.4 18.3 16.6 12.8 8.5 5.1
    10 3.3 2.5 2.6 4.4 7.2 9.2 10.7 13.0 14.7 12.7 8.5 5.2
    16 3.4 2.7 2.7 4.1 5.6 6.1 6.4 6.7 6.8 7.0 7.8 5.2
    20 3.5 2.8 2.8 4.0 5.2 5.6 5.8 5.9 6.0 6.1 6.5 5.2
    30 3.6 3.0 2.9 3.9 4.7 4.9 5.1 5.1 5.1 5.2 5.2 5.0
    40 3.7 3.2 2.9 3.8 4.5 4.7 4.8 4.9 4.9 4.9 4.9 4.8
  • Freezing period: January-early May (6).
  • Mixing type: Dimictic (6).

E. LAKE WATER QUALITY

E1 TRANSPARENCY [m](7)
    1982: 7.7 (5.2-9.9).
E2 pH (8)
    8.1-8.3.
E4 DO [mg l-1]: Fig. EUR-31-03.

    Fig. EUR-31-03
    Oxygen distribution at the deepest point in 1974 and 1975.

E6 CHLOROPHYLL CONCENTRATION (8)
  • Chlorophyll a [micro g l-1]: 1.
E7 NITROGEN CONCENTRATION (10)
  • NH4-N [micro g l-1]: Fig. EUR-31-04.

    Fig. EUR-31-04
    NH4-N distribution at the deepest point.

  • NO3-N [micro g l-1]: Fig. EUR-31-05.

    Fig. EUR-31-05
    NO3-N distribution at the deepest point.

E8 PHOSPHORUS CONCENTRATION (11)
  • PO4-P [micro g l-1]: Fig. EUR-31-06 and 07.

    Fig. EUR-31-06
    PO4-P distribution at the deepest point.

    Fig. EUR-31-07
    Total-P distribution at the deepest point.

E1O PAST TRENDS

    Fig. EUR-31-08
    Past trend of transparency [m](7).

    Fig. EUR-31-09
    Past trends of oxygen saturation (hatched part) and concentration (unhatched) at the end of summer stagnation period (November) in deep water (60 m)(9).

    Fig. EUR-31-10
    Past trends of maximum PO4-P concentration at the beginning of the spring full circulation and maximum Total-P concentration [micro g l-1] at the end of spring full circulation (11).

    Fig. EUR-31-11
    Past trends of PO4-P and Total-P concentrations [micro g l-1] at the end of the summer stagnation period (November/December), at 60 m depth (11).


F. BIOLOGICAL FEATURES

F1 FLORA
  • Emerged macrophytes (12)
    Cladium mariscus, Carex acutiformis, Thelypteris palustris, Phragmites australis, Typha angustifolia, Equisetum fluviatile, Sparganium minimum, Hydrocharis morsusranae.
  • Floating macrophytes: Lemna minor, L. trisulca, Spirodela polyrhiza (12).
  • Submerged macrophytes (12)
    Utricularia vulgaris, Ceratophyllum demersum, Chara fragilis, C. vulgaris, C. aspera, Myriophyllum spicatum, Nitellopsis obtusa.
  • Phytoplankton (13)
    Anabaena lemmermannii, Asterionella formosa, Chrysamoeba radians, Cyclotella kutzingiana, Dinobryon bavaricum, D. cylindricum, Mallomonas fastigata, Oscillatoria rubescens, Scenedesmus costato-granulatus, Synedra acus, Crucigenia quadrata.
F2 FAUNA
  • Zooplankton (14)
    Eudiaptomus gracilis, Eurytemora lacustris, Daphnia cucullata, Synchaeta pectinata, Ascomorpha ecaudis, Pompholyx sulcata, Polyarthra dolichoptera, Conochilus unicornis, Filinia terminalis, Keratella cochlearis, Kellicottia longispina.
  • Benthos (15)
    Pisidium conventus, Sergentia coracina, Stictochironomus rosenscholdi, S. histrio, Enallagma cyathigerum, Coenagrion puella, C. pulchellum.
  • Fish (16)
    Abramis brama, Anguilla anguilla, Coregonus albula, Cyprinus carpio, Esox luceus, Rutilus rutilus, Perca fluviatilis, Tinca tinca, Lucioperca lucioperca.
F3 PRIMARY PRODUCTION RATE: Fig. EUR-31-12.

    Fig. EUR-31-12
    Spatial and temporal distribution of primary production of phytoplankton [mg m-3 d-1](17).

F4 BIOMASS: Fig. EUR-31-13.

    Fig. EUR-31-13
    Seasonal periodicity of phytoplankton biovolume [trill. micro m3 m-2], cell and colony number [bill. m-2](13).

F5 FISHERY PRODUCTS: Fig. EUR-31-14.

    Fig. EUR-31-14
    Mean yield of European Cisco [kg yr-1](16).

F6 PAST TRENDS: Fig. EUR-31-15 (17).

    Fig. EUR-31-15
    Seasonal periodicity of primary production of phytoplankton (and cooling water input from the nuclear power station)[g m-2 d-1].

F7 NOTES ON THE REMARKABLE CHANGES OF BIOTA IN THE LAKE IN RECENT YEARS
    In 1966 the first nuclear power plant in the G. D. R. was put into operation with an external circulation of its cooling water taken from Lake Nehmitz. The heated water is then introduced into Lake Stechlin (Fig. EUR-31-17).
    The phenomena observed concerning the phytoplanktonic community after the start of the nuclear power plant operation (1966) can be summed up as follows. The phytoplanktonic periodicity corresponds well with the cooling water circulation. When the nuclear power plant is in operation the spring development of phytoplankters starts nearly six weeks earlier than under natural conditions. Every interruption of the cooling water circulation is followed by a break of continuity of phytoplankton development (13).

    Fig. EUR-31-16
    Comparison between primary production of phytoplankton and periphyton and orthphosphate concentration in close-to-surface layer of the Lake Stechlin- system as influenced by the cooling water circulation (18).

Average annual production of macrozoobenthos in the west basin before and after the nuclear power plant has become operational (18).
    Macrozoobenthos Before operation (mg ww m-2 yr-1) After operation (mg ww m-2 yr-1) Relative change (%)
    Pisidium conventus 54 263 487
    Oligochaeta 589 3,106 527
    Sergentia coracina 141 778 552
    Tanytarsini 363 287 79
    Total 1,147 4,434 387
    *ww: wet weight.

G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA (19)
  • Main types of woody vegetation
    Evergreen conifer forest (Pinus sylvestris).
G3 POPULATION IN THE CATCHMENT AREA (20)
    1989
    Population Population density [km-2] Major cities (population)
    Total 1,095 42.1 None (415,000 visitors during summer season, in 1980)

H. LAKE UTILIZATION

H1 LAKE UTILIZATION (8, 21)
    Source of water, cooling water circulation, sightseeing and tourism, recreation (swimming, sport-fishing, yachting) and fisheries.

    Fig. EUR-31-17
    Mean increase of surface water temperature by thermal discharge [deg C](6).

Lake Stechlin area: trend in recreation-days (8)
    Holiday-makers Short-time Diving centre
    Year overnight visitors visitors
    1963 60,000 10,000 -
    1975 230,000 40,000 -
    1980 350,000 60,000 5,000
H2 THE LAKE AS WATER RESOURCES (8, 22)
    1982
    Use rate [m3 day-1]
    - Domestic
    Drinking (Neuglobsow) N.A.
    - Power plant (cooling) 400,000

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS

I1 ENHANCED SILTATION (1, 8)
  • Extent of damage: None.
I2 TOXIC CONTAMINATION (1, 8)
  • Present status: None.
I3 EUTROPHICATION (11)
  • Nitrogen and phosphorus loadings to the lake
    1981, 1982

    Fig. EUR-31-18
    PO4-P load and outflow from Lake Dagow into Lake Stechlin [m3 day-1].

I4 ACIDIFICATION (8, 12)
  • Extent of damage: None.

J. WASTEWATER TREATMENTS (11)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA
    c) Limited pollution with wastewater treatment.

K. IMPROVEMENT WORKS IN THE LAKE

K3 OTHERS (8)
    Sewage diversion in the catchment area (1985).

L. DEVELOPMENT PLANS (1, 8)

    None.

M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M1 NATIONAL AND LOCAL LAWS CONCERNED (8)
  • Main items of control
    Toxic substances in the effluents (phenols, detergents, Cu, Cr, Pb, As, Zn, Cd, Co, Ni, Hg, polycyclic aromatic hydrocarbons, organophosphoric hydrocarbons, fluoride). Pollutants in the effluents (N, P, BOD salinity, Ca, Mg, Na, chloride, sulphate, hardness, Fe, Mn, pH-value). Bacteriological criteria (coliforms, enterococci).
M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES (21)
  1. Limnological Laboratory Stechlin
  2. Hydrometorological Station of Meterological Service
  3. Ministry of Higher Education
  4. Ministry of Environment and Water Management
  5. Academy of Science
  6. Department of Water Science of Technology, University Dresden
  7. Institute of Water Management, Berlin

N. SOURCES OF DATA

  1. Questionnaire prepared by the editors with the support of Dr. W. Scheffler, Akademie der Wissenschaften der DDR, Zentralinstitut fur Mikrobiologie und Experimentelle Therapie, Jena, DDR, based on the following sources.
  2. Krey, L. (1985) The lakes of the Lake Stechlin area: aspects of their morphometry. "Lake Stechlin" (ed. Casper, S. J.), pp. 29-40. Dr W. Junk Publishers, Dordrecht.
  3. Krey, L. (1985) Morphology and morphogenesis of the Lake Stechlin area. Ibid., pp. 7-10.
  4. Richter, D. (1985) Climatic conditions. Ibid., pp. 41-47.
  5. Richter, D. (1985) Water balance components. Ibid., pp. 67-72.
  6. Richter, D. (1985) Heat balance components. Ibid., pp. 56-64.
  7. Richter, D. (1985) Water temperature. Ibid., pp. 47-56.
  8. Koschel, R. (1985) Light penetration. Ibid., pp. 72-86.
  9. Klapper, H. & Koschel, R. (1985) Lake Stechlin area and society. Ibid., pp. 455-483.
  10. Mothes, G. & Koschel, R. (1985) The oxygen budget. Ibid., pp. 118-125.
  11. Mothes, G & Koschel, R. (1985) The nitrogen budget. Ibid., pp. 111-116.
  12. Koschel, R. & Mothes, G. (1985) The phosphorus budget. Ibid., pp. 87- 101.
  13. Krausch, H.-D. (1985) Aquatic macrophytes in the Lake Stechlin area. Ibid., pp. 129-149.
  14. Casper, S. J. (1985) The phytoplankton. Ibid., pp. 157-195.
  15. Ronneberger, D. & Kasprzak, P. (1985) The zooplanktonic population. Ibid., pp. 243-259.
  16. Mothes, G. (1985) The macrozoobenthos. Ibid., pp. 230-243.
  17. Ronneberger, D. (1985) Fish. Ibid., pp. 261-269.
  18. Koschel, R. (1985) The primary production of the phytoplankton. Ibid., pp. 287-314.
  19. Koschel, R., Mothes, G. & Casper, S. J. (1985) The nuclear power plant and its role in the life of Lake Stechlin. Ibid., pp. 419-429.
  20. Krausch, H.-D. (1985) The plant cover of the Lake Stechlin area. Ibid., pp. 11-15.
  21. (1989) Personal communication.
  22. Krausch, H.-D. (1985) Settlement and economy of the Lake Stechlin area. Ibid., pp. 15-18.
  23. Casper, S. J. (1985) The Limnological Laboratory Stechlin and the Lake Stechlin research project. Ibid., pp. 19-24.