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SHUMARINAI-KO (LAKE SHUMARINAI)

A lake view from the eastern hill-side
Photo.
Photo: A. Kurata

A. LOCATION

  • Hokkaido, Japan.
  • 44:20N, 142:13E; 285 m above sea level.

B. DESCRIPTION

Lake Shumarinai is the only man-made lake in Hokkaido, Japan. It was formed by the construction of Uryu Dam in the upstream of Uryu River to serve as a reservoir for hydroelectric power generation. The lake is called generally Shumarinai-ko, but it is also called formally the First Uryu Reservoir. The dam construction was initiated in 1937 and completed in 1943 by Hokkaido Electric Company. The lake now supplies irrigation water at an average rate of 9.73 m3 sec-1 only for summer season from May to August together with hydroelectric power. It also plays an important role to prevent flood in the downstream area at the time of spring thaw.

The lake is located about 20 km west of Nayoro City. With 13 islands, the lake is irregularly arborescent in shape. The area surrounding the lake is designated as a prefectural natural park for preserving wildlife and other natural resources. Not only hunting and capture of animals but also deforestation are strictly prohibited.

The climate of Lake Shumarinai is characterized by severe, long winter and dry, short summer. The lake freezes regularly from late autumn to late spring. Horokanai Town located on the shore of this lake is so famous as one of the coldest places in Japan; an air temperature of -41.2deg C was recorded in the town in 1978.

The catchment area of reservoir (312.1 km2) is sparsely populated and largely covered by dense forest, containing only a small part of agricultural land. The water has remained oligotrophic, chlorophyll and total phosphorus concentration being very low (Q, 1).

C. PHYSICAL DIMENSIONS (Q)

Surface area [km2] 24
Volume [km3] 0.2447
Water level Regulated
Normal range of annual water
- level fluctuation [m] 11
Length of shoreline [km] 83.5
Residence time [yr] 68
Catchment area [km2] 312

D. PHYSIOGRAPHIC FEATURES (Q)

D1 GEOGRAPHICAL

  • Sketch map: Fig. ASI-33-01.
  • Names of main islands: Fujiwara-jima and Kitao-shima.
  • Number of outflowing rivers and channels (names): 1 (Uryu R.).

D2 CLIMATIC

  • Climatic data at the lake side, 1975-1976
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
Mean temp. [deg C] -11.3 -12.0 -5.8 2.3 8.8 14.9 18.7 18.3 14.1 7.5 0.1 -6.2 4.1
Precipitation [mm] 80 45 63 69 70 84 83 197 152 169 134 82 1,228

    Fig. ASI-33-01
    Sketch map (Q).
  • Water temperature [deg C]
Several stations, 1982
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0 - - - - - 16.3 - - - - - -
5 - - - - - 14.9 - - - - - -
30 - - - - - 6.5 - - - - - -
  • Freezing period: November-May.

E. LAKE WATER QUALITY (Q)

E1 TRANSPARENCY [m]

Station 1, 1982
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
- - - - - 5.0 - - - - - -

E2 pH

Station 1, 1982
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0 - - - - - 7.2 - - - - - -
5 - - - - - 7.1 - - - - - -
25 - - - - - 6.6 - - - - - -

E3 SS [mg l-1]

Station 1, 1982
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0 - - - - - 2 - - - - - -
5 - - - - - 2 - - - - - -
25 - - - - - 8 - - - - - -

E4 DO [mg l-1]

Station 1, 1982
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0 - - - - - 9.0 - - - - - -
5 - - - - - 9.1 - - - - - -
25 - - - - - 8.1 - - - - - -

E5 COD [mg l-1]

Determined by KMnO4 method.

Station 1, 1982
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0 - - - - - 1.6 - - - - - -
5 - - - - - 1.7 - - - - - -
25 - - - - - 1.8 - - - - - -

E6 CHLOROPHYLL CONCENTRATION [micro l-1]

Station 1, 1982
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0 - - - - - 1.32 - - - - - -
5 - - - - - 1.02 - - - - - -
25 - - - - - 0.72 - - - - - -

E7 NITROGEN CONCENTRATION

  • Total-N [mg l-1]
Station 1, 1982
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0 - - - - - 0.11 - - - - - -
5 - - - - - 0.13 - - - - - -
25 - - - - - 0.38 - - - - - -

E8 PHOSPHORUS CONCENTRATION

  • Total-P [mg l-1]
Station 1, 1982
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0 - - - - - 0.008 - - - - - -
5 - - - - - 0.013 - - - - - -
25 - - - - - 0.007 - - - - - -

F. BIOLOGICAL FEATURES (1)

F2 FAUNA

  • Fish: Oncorhynchus masou, Tribolodon hakonensis, Cyprinus carpio, Hypomesus transpacificus nipponensis, Salvelinus leucomaenis, Hucho Perryi, Gasterosteus aculeatus aculeatus.

F5 FISHERY PRODUCTS

  • Annual fish catch [metric tons]
    1982: 17.3.

G. SOCIO-ECONOMIC CONDITIONS (1)

G1 LAND USE IN THE CATCHMENT AREA

Area[km2] [%]
Natural landscape
- Woody vegetation 225.58 72.3
Agricultural land 4.80 1.53
Residential area 0.13 0.04
Others 81.57 26.13
Total 312.08 100
  • Main types of woody vegetation
    Evergreen forest (Abies sachalinensis); deciduous forest (Ulmus davidiana, Sorbus commixta, Acer mono, Fraxinus mandshurica, Alnus maximowiczii, Morus bombycis).

G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE

  • Numbers of domestic animals in the catchment area: Cattle 438.

G3 POPULATION IN THE CATCHMENT AREA

1981
Population Population density [km-2] Major cities (population)
Total 152 0.5 None

H. LAKE UTILIZATION

H1 LAKE UTILIZATION (1)

Source of water, fisheries and sight-seeing.

H2 THE LAKE AS WATER RESOURCE (2)

1984
Use rate [m3 sec-1]
Irrigation 9.73(May-August)
Power plant 12.0 (0-44.2)

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS

I1 ENHANCED SILTATION

: No information.

I2 TOXIC CONTAMINATION (1)

: None.

I3 EUTROPHICATION (1)

: None.

I4 ACIDIFICATION (1)

: None.

J. WASTEWATER TREATMENTS (1)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA

a) Pristine lake environments.

J3 SANITARY FACILITIES AND SEWERAGE

  • Percentage of rural population with adequate sanitary facilities (on-site treatment systems): 100%.

M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M1 NATIONAL AND LOCAL LAWS CONCERNED

For national laws see "Biwa-ko".

N. SOURCES OF DATA

Questionnaire filled by the Prefectural Government of Hokkaido.

  1. The editor's observation.
  2. The First Uryu Dam Control Office of Hokkaido Electric Co., Ltd. Personal communication.
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