SAROMA-KO (LAKE SAROMA)

A lake view from the south-eastern shore

Photo.
Photo: A. Kurata


A. LOCATION

  • Hokkaido, Japan.

  • 44:15N, 143:33E; 0 m above sea level.


B. DESCRIPTION

    Lake Saroma is the third largest lake of Japan located on the north-eastern shore of Hokkaido about 30 km away from Abashiri City. The lake is very shallow for its size (maximum depth 19.5 m, mean depth 8.7 m), and is separated from the Sea of Okhotsk by a 20 km-long sandbar (only 150-500 m wide). A narrow opening through the sandbar makes the lake water brackish with a normal chloride concentration of 17-18%. The lake is mesotrophic, as indicated by a normal transparency value of about 6 m, and is known for various kinds of aquaculture (oyster, scallop, smelt, laver, etc.).
    Extensive stands of a halophyte, Salicornia europaea, with succulent stems and small scale-like leaves turn coastal salt marsh of the lake into deep red with its autumnal color. The lake is surrounded by wide reed zone and deciduous forests with many oak trees. It is included in Abashiri Quasi-national Park, designated by the Prefectural Government of Hokkaido for its scarcely populated wild natural landscape (Q, 2).


C. PHYSICAL DIMENSIONS (Q)

    Surface area [km2] 150
    Volume [km3] 1.3
    Maximum depth [m] 19.5
    Mean depth [m] 8.7
    Water level Unregulated
    Length of shoreline [km] 82.4
    Catchment area [km2] 618

D. PHYSIOGRAPHIC FEATURES (Q)

D1 GEOGRAPHICAL
  • Bathymetric map: Fig. ASI-36-01.<
    • BR>
  • Names of main islands: None.

  • Number of outflowing rivers and channels (name): 1.

D2 CLIMATIC
  • Climatic data at Abashiri, 1983-1985

    • Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    Mean temp. [deg C] -7.7 -7.6 -3.6 5.0 8.9 12.4 16.6 20.4 15.2 9.0 3.0 -3.7 5.7
    Precipitation [mm] 141 155 206 220 211 189 198 238 196 178 143 135 2,210
  • Number of hours of bright sunshine: 2,209 hr yr-1.

    Fig. ASI-36-01
    Bathymetric map (1).

  • Water temperature [deg C]

    • Station 1
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 8.4 12.6 17.6 19.2 18.0 - 8.1 -
    2 - - - - 8.2 12.5 16.7 19.0 17.9 - 7.2 -
    Station 2, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 8.8 12.8 16.6 19.4 18.0 - 8.1 -
    2 - - - - 8.8 12.8 15.6 19.1 17.7 - 8.1 -
  • Freezing period: December-March.

  • Mixing type: Dimictic.


E. LAKE WATER QUALITY (Q)

E1 TRANSPARENCY [m]
    Station 1, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    - - - - 4.9 6.3 5.2 6.2 5.1 - 6.1 -
    Station 2, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    - - - - 5.4 6.9 5.5 6.1 5.8 - 6.2 -
E2 pH
    Station 1, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 8.3 8.1 8.2 8.2 8.2 - 8.1 -
    2 - - - - 8.3 8.2 8.3 8.2 8.2 - 8.0 -
    Station 2, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 8.3 8.2 8.3 8.2 8.2 - 8.1 -
    2 - - - - 8.4 8.2 8.3 8.2 8.2 - 8.1 -
E3 SS [mg l-1]
    Station 1, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 2 1 2 1 3 - - -
    2 - - - - 2 2 3 1 3 - - -
    Station 2, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 2 1 4 2 2 - 6 -
    2 - - - - 1 2 2 2 2 - 6 -
E4 DO [mg l-1]
    Station 1, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Oct Sep Nov Dec
    0 - - - - 10.1 9.0 8.3 8.2 8.4 - 9.0 -
    2 - - - - 9.9 9.1 8.7 8.1 8.3 - 9.0 -
    Station 2, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 9.9 9.3 8.9 8.1 8.5 - 8.8 -
    2 - - - - 10.2 9.1 9.1 8.3 8.3 - 8.9 -
E5 COD
    Determined by KMnO4 method
    Station 1, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 1.8 1.5 2.0 1.9 1.2 - 2.2 -
    2 - - - - 1.0 1.9 1.5 2.2 1.1 - 2.1 -
    Station 2, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 1.3 1.7 1.6 1.9 0.9 - 1.9 -
    2 - - - - 1.3 2.0 1.8 1.8 1.1 - 2.2 -
E7 NITROGEN CONCENTRATION
  • Total-N [mg l-1]

    • Station 1, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 0.17 0.13 0.10 0.05 0.15 - 0.18 -
    2 - - - - 0.08 0.13 0.09 0.09 0.16 - 0.15 -
    Station 2, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 0.14 0.19 0.16 0.06 0.10 - 0.19 -
    2 - - - - 0.15 0.16 0.15 0.06 0.14 - 0.21 -
E8 PHOSPHORUS CONCENTRATION
  • Total-P [mg l-1]

    • Station 1, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 0.017 0.008 0.019 0.013 0.024 - 0.025-
    2 - - - - 0.011 0.011 0.016 0.018 0.038 - 0.027 -
    Station 2, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 0.009 0.008 0.016 0.021 0.025 - 0.021 -
    2 - - - - 0.010 0.007 0.015 0.020 0.024 - 0.024 -
E9 CHLORIDE CONCENTRATION [ ]
    Station 1, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 17.5 18.2 18.3 18.3 17.9 - 18.3 -
    2 - - - - 17.5 18.2 18.3 18.3 18.0 - 18.2 -
    Station 2, 1983-1985
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0 - - - - 17.2 18.3 18.2 18.4 17.8 18.2 -
    2 - - - - 17.4 17.9 18.2 18.3 17.9 18.2 -

F. BIOLOGICAL FEATURES (Q)

F1 FLORA
  • Emerged macrophytes: Phagmites sp.

  • Submerged macrophytes: Zostera marina, Potamogeton crispus.

  • Phytoplankton: Diatoms.

F2 FAUNA
  • Zooplankton: Copepoda, veliger of bivalvia and gastropoda.

  • Benthos
    Corbicula japonica, Batillaria multiformis, Littorina squalida, Macoma incongrua, Nuttallia olivacea.
  • Fish
    Pleuronectidae, Clupea pallasi, Hypomesus olidus, H. pretiosus japonicus, Eleginus gracilis, Oryzias latipes, Cottus pollux.

G. SOCIO-ECONOMIC CONDITIONS (Q)

G1 LAND USE IN THE CATCHMENT AREA
    Area [km2] [%]
    Natural landscape
    - Woody vegetation 385.99 62.4
    Agricultural land
    - Crop field 124.01 20.1
    Residential area 2.34 0.4
    Others 106.04 17.1
    Total 618.38 100
  • Main types of woody vegetation
    Deciduous forest (Betula ermanii, Quercus mongolica, Acer ukurunduense, Cornus controversa) and larch (Larix Kaempferi) plantation.
G3 POPULATION IN THE CATCHMENT AREA
    Population Population density [km-2] Major cities (population)
    Total 8,900 14.4 None

H. LAKE UTILIZATION (Q, 2)

H1 LAKE UTILIZATION
    Fisheries, tourism and recreation (swimming, sport-fishing, yachting).

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS (Q, 2)

I1 ENHANCED SILTATION: No information.

I2 TOXIC CONTAMINATION
  • Present status: None.

I3 EUTROPHICATION: No information.
I4 ACIDIFICATION
  • Extent of damage: None.


J. WASTEWATER TREATMENTS (Q)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA
    b) No sources of significant pollution.
J3 SANITARY FACILITIES AND SEWERAGE: No information.

M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS (Q)

M1 NATIONAL AND LOCAL LAWS CONCERNED
    For national laws see "Biwa-ko".

N. SOURCES OF DATA

  1. Questionnaire filled by Prefectural Government of Hokkaido.
  2. Geogr.Survey. Inst., Ministry of Construction (1971) 1:10,000 Map of Lake Saroma (1:10,000 Kosho zu, Saroma-ko).*
  3. The editors' observation.

    4. * printed in Japanese. The titles are tentatively translated into English with the original titles in romanized Japanese in parentheses.