KAMAFUSA DAMU-KO

An aerial view of the dam site >Photo. Photo: Miyagi Prefectural Government  
 

A. LOCATION

  • Miyagi Prefecture, Japan.
  • 39:12-N, 140:42-E; 149 m above sea level.
 

B. DESCRIPTION

    Kamafusa Damu-ko (Reservoir) was constructed by the Ministry of Construction on the Goishi River of the Natori River System in 1970 as a multi-purpose reservoir for flood control, irrigation, domestic and industrial water supply, and electric power generation at a cost of 8.72 billion yen. Construction began in 1966 and the reservoir was filled in 1970.
    The reservoir is located among low hills 10 km southwest of Sendai City. The prevailing climate is characterized by hot wet summers and rather mild winters when the reservoir seldom freezes over.
    It supplies drinking water for Sendai and its suburban areas and offers an important recreational park area for both Sendai citizens and local residents with various facilities for camping, boating and sport fishing. The water quality of the reservoir has become seriously eutrophic owing to heavy nutrients loads, particularly from non-point sources, failing to meet the lake water quality standards required by the national law in recent years. Remedial measures have therefore been carried out by Miyagi Prefectural Government, including sediment dredging, installation of intermittent aeration system, and biomanipulation using certain plants and animals. The construction of wastewater treatment plants for livestock pens is also encouraged. The Committee for Environmental Conservation in Kamafusa Damu-ko, established in 1989, is responsible for the promotion of conservation works, recreational development, environmental concern of the public and related citizens activities (Q, 12).
 

C. PHYSICAL DIMENSIONS (1)

     
    Surface area [km2] 3.9
    Volume [km3] 0.0453
    Maximum depth [m] 42.8
    Mean depth [m] 11.6
    Water level Regulated
    Normal range of annual water level fluctuation [m] 6.0
    Length of shoreline [km] 28
    Residence time [yr] 0.18
    Catchment area [km2] 191.4
     
 

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL
  • Bathymetric map: Fig. ASI-59-1.
  • Number of main islands: None.
  • Number of outflowing rivers and channels (name): 1 (Goishi R.).

Fig-ASI-59-1 Bathymetric map.

D2 CLIMATIC

  • Climatic data at Kamafusa, 1984 1986 (1)
     
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov De Ann.
    Mean temp. [deg C] -1.4 -0.7 2.1 8.7 14.1 17.8 22.2 25.3 19.8 12.9 7.5 3.0 10.9
    Precipitation [mm] 29 96 78 109 123 141 155 155 187 104 59 31 1,264
     
  • Number of hours of bright sunshine (Kawasaki): 1,804 hr yr-1 (2).
  • Water temperature [deg C]
     
    Dam site, 1984 1986
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    S*1 1.9 2.2 3.2 10.6 13.8 20.1 20.8 26.1 22.4 17.4 12.1 7.1
    M*2 2.2 2.1 3.4 7.3 9.1 10.5 15.3 17.0 19.3 15.8 11.7 6.9
    B*3 2.6 2.2 3.4 6.3 7.4 8.6 12.6 14.6 15.8 14.8 11.1 6.3
    *1 Surface: 0.5 m. *2 Middle: One half of the water depth. *3 Bottom: 1 m above the bottom.
  • Freezing period: None (1).
  • Mixing type: Monomictic (1).
  • Notes on water mixing and thermocline formation (1)

    • Due to the operation of intermittent aeration pipes, the thermocline has been lowered.
 

E. LAKE WATER QUALITY

E1 TRANSPARENCY [m](1)
     
    Dam site, 1984 1986
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    2.5 2.8 3.4 2.5 2.5 2.2 1.6 1.4 1.4 1.8 1.9 2.3
     
E2 pH
     
    Dam site, 1984 1986
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    S*1 7.2 7.1 7.2 7.1 7.2 8.1 7.2 7.3 7.7 7.3 7.2 7.0
    M*2 7.3 7.2 7.3 7.0 7.0 7.1 7.1 6.8 7.1 7.2 7.2 7.3
    B*3 7.2 7.2 7.2 7.1 7.0 6.9 6.9 6.8 6.9 7.2 7.2 7.0
    *1 Surface. *2 Middle. *3 Bottom.
E3 SS [mg l-1](1)
     
    Dam site, 1984 1986
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    S*1 3 4 2 3 4 8 3 16 6 4 5 4
    M*2 3 3 3 3 3 1 8 45 13 8 5 4
    B*3 4 3 2 3 3 1 33 73 28 21 13 5
    *1 Surface. *2 Middle. *3 Bottom.
E4 DO [mg l-1]
     
    Dam site, 1984 1986
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    S*1 12.8 13.2 12.9 11.8 11.6 10.8 9.8 8.8 8.0 9.0 10.2 11.6
    M*2 12.8 13.1 12.8 10.9 10.3 7.6 7.2 6.9 5.9 8.3 9.8 11.4
    B*3 12.5 13.1 12.5 10.7 9.5 7.3 5.2 5.5 1.7 8.0 9.4 11.6
    *1 Surface. *2 Middle. *3 Bottom.
E5 COD [mg l-1]
    Determined by KMnO4 method.
     
    Dam site, 1984 1986
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    S*1 1.5 1.6 1.6 1.7 2.6 4.2 3.0 3.0 3.0 2.7 2.4 1.9
    M*2 1.6 1.6 1.4 1.4 1.5 1.4 2.0 2.3 2.4 2.2 2.3 1.8
    B*3 1.8 1.5 1.6 1.3 1.3 1.3 2.7 2.6 2.4 2.9 2.1 1.8
    *1 Surface. *2 Middle. *3 Bottom.
E6 CHLOROPHYLL CONCENTRATION [micro l-1](3)
     
    Dam site, 1984 1986
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    S*1 2.1 1.9 2.3 5.9 3.7 11.0 5.9 3.7 6.5 3.8 4.3 5.6
    M*2 2.3 1.7 2.7 3.5 2.8 3.2 1.8 1.1 1.9 2.9 4.1 5.9
    B*3 2.9 1.8 1.9 2.0 0.8 0.6 1.1 0.4 0.9 0.7 3.1 4.2
    *1 Surface. *2 Middle. *3 Bottom.
E7 NITROGEN CONCENTRATION (1)
  • Total-N [mg l-1]
     
    Dam site, 1984 1986
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    S*1 0.38 0.44 0.52 0.55 0.45 0.40 0.50 0.59 0.73 0.60 0.46 0.45
    M*2 0.37 0.46 0.50 0.60 0.44 0.60 0.69 0.78 0.68 0.54 0.44 0.42
    B*3 0.42 0.45 0.54 0.60 0.53 0.49 0.68 0.80 0.79 0.53 0.50 0.40
    *1 Surface. *2 Middle. *3 Bottom.
E8 PHOSPHORUS CONCENTRATION (1)
  • Total-P [micro l-1]
     
    Dam site, 1984 1986
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    S*1 10 10 8 11 14 21 23 34 23 21 16 11
    M*2 9 9 8 9 7 6 18 41 33 22 14 11
    B*3 10 10 12 7 6 7 23 57 33 34 21 11
    *1 Surface. *2 Middle. *3 Bottom.
 

F. BIOLOGICAL FEATURES

F1 FLORA (1)
  • Phytoplankton

    • Asterionella sp., Melosira sp., Lyngbya sp., Phormidium sp.
F2 FAUNA (1)
  • Zooplankton: Polyarthra sp.
  • Fish: Carassius auratus cuvieri, Cyprinus carpio, Hypomesus nipponensis.
F7 NOTES ON THE REMARKABLE CHANGES OF BIOTA IN THE LAKE IN RECENT YEARS (4)
    The bloom of Phormidium has ceased since 1985. The increase of Lyngbya, which used to start in late October before 1984, began to occur over a longer period from July to late December since 1985.
 

G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA* (5, 6, 7) (1980)
     
    Area [km2] [%]
    Natural landscape
    - Woody vegetation 219.74 81.1
    - Herbaceous vegetation 0.25 0.1
    - Others 9.46 3.5
    Agricultural land
    - Crop field 22.00 8.1
    - Pasture 0.07 0.03
    Residential area 5.30 2.0
    Others 14.16 5.2
    Total 270.98 100
    * Including all the area of Kawasaki town.
  • Main types of important forest vegetation

    • Secondary deciduous broadleaf forest (Quercus serrata, Castanea crenata).
  • Main kinds of crops: Rice.
  • Levels of fertilizer application on crop fields: Moderate.
G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE (8, 9) (1985)
     
    Gross production during the year [x1.0E+6 yen] No. of persons No. of establishments Main products and major industries
    Primary industry 4,400 2,059 1,312
    - Crop production 2,669 N.A. N.A. Rice
    - Annual husbandry 1,729 N.A. N.A. Cow
    - Others 2 N.A. N.A.
    Secondary industry 20,670 1,414 35 Electromecha nical industry
    Tertiary industry 4,427 457 179
     
  • Number of domestic animals in the catchment area

    • Cattle 3,893, swine 28, poultry 179,272.
G3 POPULATION IN THE CATCHMENT AREA (10) (1985)
    Total population (rural): 10,939; population density 57.2 [km 2].
 

H. LAKE UTILIZATION (1)

H1 LAKE UTILIZATION
    Source of water and recreation (sport-fishing).
H2 THE LAKE AS WATER RESOURCE (1986)
     
    Use rate [m3 sec 1]
    Domestic 1.91
    Irrigation 3.23
    Industrial 0.17
    Power plant 5,700 [MWh]
     
 

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS

I1 ENHANCED SILTATION (1)
  • Extent of damage: None.
I2 TOXIC CONTAMINATION (11)
  • Present status: Undetected.
  • Main contaminants and their concentrations
     
    Dam Site, 1985
    Name of contaminant Concentration in water [ppm]
    Cd <0.005
    Cyanides N. D.
    Organic-P N. D.
    Pb 0.05
    Cr6+ <0.02
    As <0.02
    Total Hg <0.0005
    Alkyl Hg N. D.
    PCB N. D.
     
I3 EUTROPHICATION (Q)
  • Nuisance caused by eutrophication

    • Disturbed filtration in cleaning beds for tap water; foul smell of tap water.
  • Nitrogen and phosphorus loadings to the lake [kg yr-1] (1986)
     
    Source Industrial Domestic Agricultural Natural Total
    T-N 3,869 19,704 112,575 69,994 206,169
    T-P 1,476 2,501 2,681 2,633 9,291
     
I4 ACIDIFICATION
  • Extent of damage: None.
 

J. WASTEWATER TREATMENTS (Q)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA
    (c) Limited pollution with wastewater treatment.
J2 APPROXIMATE PERCENTAGE DISTRIBUTION OF POLLUTANT LOADS
     
    COD
    Sources [t yr-1] [%]
    Natural fall 587 73
    Domestic wastewater 94 12
    Industrial wastewater 8 1
    Agricultural runoff 55 7
    Wastewater from livestock farming 59 7
    Total 803 100
     
J3 SANITARY FACILITIES AND SEWERAGE
  • Percentage of population in the catchment area provided with adequate sanitary facilities or public sewerage: 24%.
  • Industrial wastewater treatment systems

    • 11 (septic tank, concentrate precipitation).
 

K. IMPROVEMENT WORKS IN THE LAKE (1)

K2 AERATION
    An intermittent aeration pipe system was introduced in 1984. Five pipes are operated at present.
 

L. DEVELOPMENT PLANS (Q)

    A lake-side park has been developed by the National Government.
 

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

M1 NATIONAL AND LOCAL LAWS CONCERNED
  • Names of the laws (the year of legislation)
    1. See "Biwa-ko" concerning national laws.
  • Responsible authorities
    1. Miyagi Prefectural Government
  • Main items of control
    1. COD
M2 INSTITUTIONAL MEASURES
  1. Ministry of Construction, Tohoku Regional Construction Bureau, Sendai
  2. Miyagi Prefectural Government, Department of Public Health and Environment, Sendai
M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES
  1. Miyagi Prefectural Institute of Public Health and Environment

    2. Sendai Municipal Waterworks Bureau

    N. SOURCE OF DATA

    Cited publications were all printed in Japanese. The titles are tentatively translated into English with the original titles in romanized Japanese in parentheses.

    (Q) Questionnaire filled by Division of Environmental Management, Department of Public Health and Environment, Miyagi Prefectural Government, Sendai
    (1) Provided by Kamafusa Damu-ko Management Station, Ministry of Construction.
    (2) Nippon Meteorological Association, Tohoku Branch (1984-86) Monthly Meteorological Report of Miyagi Prefecture (Miyagi-ken Kisho Geppo).
    (3) Sendai Municipal Waterworks Bureau (1984-86) Annual Water Quality Report (Suishitsu Nenpo).
    (4) According to Sendai Municipal Waterworks Bureau.
    (5) Land Use Plan of Kawasaki Town, Miyagi Prefecture (Kawasaki-cho Kokudo Riyo Keikaku)
    (6) Miyagi Prefectural Government (1980) In Pursuit of Comfortable Environments (Kaitekina Kankyo wo motomete).
    (7) Miyagi Prefectural Government (1984) Report of the Scientific Survey on the Prefectural Nature Conservation Area at Kamafusa Lake (Kamafusa-ko Ken Shizen Hozen Chiiki Gakujyutu-chosa Hokokusho).
    (8) Miyagi Prefectural Government (1987) Statistical Yearbook (Miyagi-ken Tokei Nenpo).
    (9) Planning Bureau, Miyagi Prefectural Government (1985) Report of Agricultural Census (Nogyo Sensasu Hokokusho)
    (10) Results of the National Census in 1985 for Kawasaki Town.
    (11) Miyagi Prefectural Government (1985) Report of the Water Quality Observation in Public Water Bodies (Kokyoyo Suiiki Suishitsu Sokutei-kekka Hokokusho).
    (12) The editor's observation.