KASUMIGAURA (LAKE KASUMIGAURA)

A view at the lake center


Photo: A. Kurata  
 

A. LOCATION

• Ibaraki Prefecture, Japan.
• 35:52-36:09N, 140:13-140:38E; 0.16 m above sea level.

 

B. DESCRIPTION

>Kasumi-ga-ura (lake of Kasumi) is the second largest lake of Japan located about 60 km northeast of Tokyo. The general name "Kasumigaura" is used to include altogether the main lake (Nishiura), two attached lakes (Kitaura and Sotonasakaura) and the rivers connecting them. These lakes once formed a deep marine bay, but have since been cut off from the sea by the sedimentation of adjacent rivers and the progress of tectonic subsidence since the late tertiary period. The present maximum depth is only 7 m in both Nishiura and Kitaura.
The lake water has long been used for irrigation of paddy fields in the surrounding alluvial plain and upland fields on diluvial terraces covered by thick deposits of volcanic ash. With the increase in population and industrialization around the lake's drainage basin in recent years, however, the need for rational and effective use of its water resource of some 850 million tons became pressing. The Kasumigaura Development Project thus started in 1971 for water use and flood control, and was followed by another program for improving river head areas of the lake. These enabled supplies of the lake water to the Kashima Coastal Industrial Zone, the Tokyo metropolitan area, and other new needs.
Since shallow lakes are liable to rapid eutrophication, Kasumigaura is also suffering from severe blooms of Microcystis every summer which have seriously damaged carp culture in the lake and caused foul smelling of tap water annually. Ibaraki Prefectural Government legislated the Eutrophication Prevention Act in 1981, and is making efforts to check further progress of eutrophication by reducing nitrogen and phosphorus loadings of the lake. Kasumigaura was appointed to a "designated lake" in December 1985 based on the Law Concerning Special Measures for Preserving Lake Water Quality, and measures for water quality improvement have been stepped up (Q).

 

C. PHYSICAL DIMENSIONS

 

Surface area [km2]	220
Volume [km3]	0.848
Maximum depth [m]	7
Mean depth [m]	4
Water level	Regulated
Normal range of annual water
- level fluctuation [m]	0.2-0.3
Length of shoreline [km]	252
Residence time [yr]	0.6
Catchment area [km2]	1,915

 

 

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL

• Bathymetric map: Fig. ASI-35-01.
• Number of outflowing rivers and channels (name): 1 (Hitachitone R.).

D2 CLIMATIC (2)

• Climatic data at Tsuchiura, 1973-1982

 

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Ann.
Mean temp. [deg C]	3.2	4.1	7.1	12.9	17.4	20.7	23.9	25.5	21.9	16.6	11.1	5.6	14.1
Precipitation [mm]	36	45	80	108	129	127	118	101	168	154	80	27	1,172

 

• Number of hours of bright sunshine (Tsuchiura, 1979-1982): 2308 hr yr-1.
• Solar radiation (Tateno, 1974-1980): 13.0 MJ m-2 day-1.

Fig. ASI-35-01
Bathymetric map (1).

 

• Water temperature [deg C](Q)

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	5.0	3.0	4.0	13.0	17.0	21.0	21.0	27.0	27.0	21.0	14.0	9.0

* Surface.

• Freezing period: None.
• Mixing type: Monomictic.
• Notes on water mixing and thermocline formation

The thermocline formation is none.

 

E. LAKE WATER QUALITY

E1 TRANSPARENCY [m](Q)

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
	1.1	2.0	1.2	0.9	0.8	0.9	0.9	0.7	0.6	0.3	0.6	0.6

 

E2 pH (Q)

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	7.6	7.5	7.5	7.8	8.3	8.5	8.1	8.9	9.2	8.6	7.8	7.9

* Surface.

E3 SS [mg l-1](Q)

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	4	3	5	12	14	9	13	15	14	28	22	21

* Surface.

E4 DO [mg l-1](Q)

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	10.0	11.0	12.0	9.1	9.8	9.5	7.4	8.5	7.9	9.0	10.0	10.0

* Surface.

E5 COD [mg l-1](Q)

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	6.2	5.8	6.2	6.5	7.9	7.2	7.4	10.0	12.0	11.0	9.0	8.7

* Surface.

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

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	15.0	8.0	28.0	36.0	64.0	29.0	53.0	75.0	65.0	87.0	60.0	42.0

* Surface.

E7 NITROGEN CONCENTRATION (Q)

• Total-N [mg l-1]

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	1.1	1.1	1.0	0.72	0.87	0.95	0.88	1.4	1.4	1.4	1.5	1.4

* Surface.

E8 PHOSPHORUS CONCENTRATION (Q)

• Total-P [mg l-1]

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	0.02	0.02	0.02	0.05	0.06	0.05	0.05	0.07	0.1	0.1	0.03	0.04

* Surface.

E9 CHLORIDE CONCENTRATION [mg l-1](Q)

 

Station 1, 1986
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	46.0	42.0	42.0	50.0	47.0	47.0	48.0	24.0	37.0	40.0	41.0	45.0

* Surface.

E10 PAST TRENDS : Fig. ASI-35-02, 03, 04, 05 and 06.

Fig. ASI-35-02
Trend of transparency (3, 6).

 

Fig. ASI-35-03
Trend of total COD (6).

 

Fig. ASI-35-04
Trend of T-P concentration (6).

 

Fig. ASI-35-05
Trend of NO3-N concentration (6).

 

Fig. ASI-35-06
Trend of chlorophyll a concentration (6).

 

F. BIOLOGICAL FEATURES

F1 FLORA (4)

• Emerged macrophytes

Phragmites communis, Typha latifolia, Zizania latifolia, Monochoria korsakowii.
• Floating macrophytes

Nymphoides indica, N. peltata, Hydrocharis dubia, Spirodela polyrhiza.
• Submerged macrophytes

Potamogeton perfoliatus, P. malaianus, P. maackianus, Vallisneria asiatica.
• Phytoplankton

Melosira spp., Microcystis aeruginosa, Anabaena flos-aquae, A. spiroides, Synedra rumpens, Hormidium sp.

F2 FAUNA (4)

• Zooplankton

Filinia longiseta, Trichocera birostris, Bosmina fatalis, Vorticella spp.
• Benthos

Chironomus plumosus, Tokunagayusurika akamusi, Macrobrachium nipponensis, Neomysis intermedia, Tubifex sp., Limnodrilus sp.
• Fish

Cyprinus carpio, Mugil cephalus, Hypomesus olidus, Anguilla japonica, Carassius gibelio.

F3 PRIMARY PRODUCTION RATE [g C m-2 yr-1](7)

 

Station 1, January-December
	1977*1	1978*1	1979*1	1982*2
Gross production	470	570	990	740
Respiration	(140)*3	(170)	(300)	220
Net production	(330)	(400)	(690)	520

*1 O2 method. *2 13C method. *3 ( ) is estimated.

F5 FISHERY PRODUCTS (8)

• Annual fish catch [metric tons]

1980-1985: 8,745.

F6 PAST TRENDS : Fig. ASI-35-07 and 08.

Fig. ASI-35-07
Trend of phytoplankton biomass (9).

 

Fig. ASI-35-08
Trend of fishery production (10).

 

G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA (Q)

 

1985
	Area[km2]	[%]
Natural landscape
- Highlands	861	45.0
Agricultural land
- Paddy field	466	24.3
- Farm	367	19.2
Residential area	221	11.5
Total	1,915	100.0

 

• Types of important forest (5)

Deciduous broad leaf forest (Quercus serrata, Q. acutissima, Castanea crenata, Carpinus spp.); pine forest (Pinus densiflora); evergreen broad leaf forest (Castanopsis cuspidata, Quercus spp.); evergreen conifer plantation (Pinus densiflora, P. thunbergii, Cryptomeria japonica, Chamaecyparis obtusa).
• Types of important herbaceous vegetation: Grassland and swamp (5).
• Main kinds of crops

Rice, cucumber, eggplant, peanut, watermelon, melon, Chinese cabbage, pumpkin, tomato, sweet potato, lotus rhizome.
• Levels of fertilizer application on crop fields: Heavy to moderate.
• Trends of change in land use

Wide area of watershed forest has been turned into housing lots due to the damage on pine forest by pine wilting disease and the progress of urbanization.

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

 

1985
	Gross product during the year [mill. yen]	No. of persons engaged	No. of establishments	Main products or major industries
Primary industry	-	109,000	N.A.
- Agriculture	190,400	379,000	76,966	1)
- Animal husbandry	94,800	-	-	2)
- Fisheries	5,100	-	1,112
Secondary industry	-	169,700
- Manufacturing	1,932,300	105,000	3,459	3)
Tertiary industry	N.A.	262,000	-	4)

 

1) Rice, vegetables and fruits.
2) Smelt, white bait, carp and freshwater pearl.
3) Machinery, electric wire, brewing, building stone, soy, etc.
4) Construction.

G3 POPULATION IN THE CATCHMENT AREA

 

1985
	Population	Population density [km-2]	Major cities (population)
Total	848,000	443	Tsuchiura, Tsukuba, Ishioka, Ushiku, Ryugasaki, Shimodate

 

 

H. LAKE UTILIZATION

H1 LAKE UTILIZATION (Q)

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

H2 THE LAKE AS WATER RESOURCE (Q)

 

1985
	Use rate [m3 sec-1]
Domestic	1.86
Irrigation	47.96
Industrial	6.08
Others
- Fish culture	0.16

 

 

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS (Q)

I1 ENHANCED SILTATION

• Extent of damage: None.
• Supplementary note

The sedimentation rate is estimated to be 1,000,000 [m3 yr-1]. The sediment has been dredged at a rate of 100,000 [m3 yr-1].

I2 TOXIC CONTAMINATION

• Present status: None.

I3 EUTROPHICATION

• Nuisance caused by eutrophication (Q)

Unusual bloom of Microcystis. Disturbed filtration in cleaning bed. Foul smell of tap water. Harm on fishes (1973-1974), damage to fish culture (carp).

• Nitrogen and phosphorus loadings to the lake [t yr-1](Q)

 

1981
Sources	Industrial	Domestic	Agricultural	Natural	Total
T-N	219.0	1,299.4	2,098.8	631.5	4,248.7
T-P	120.5	124.1	164.3	47.5	456.4

 

• Supplementary notes

The Ibaraki Prefectural Ordinance for the Prevention of Eutrophication of Lake Kasumigaura was enacted in 1982. The Basic Plan for Prevention of Eutrophication was also prepared at the same time to help implementation of the ordinance. A series of legislative efforts including ban on the use and selling of phosphate-containing synthetic detergents, control of nitrogen and phosphorus contents in effluent of factories, etc. has been carried out for decreasing nitrogen and phosphorus loads.

I4 ACIDIFICATION

• Extent of damage: None.

 

J. WASTEWATER TREATMENTS (Q)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA

d) Measurable pollution with limited wastewater treatment.

J2 APPROXIMATE PERCENTAGE DISTRIBUTION OF POLLUTANT LOADS

 

1985
Source	COD [t day-1]	ratio [%]
Non-point sources	23.81	75.0
(agricultural, natural and dispersed settlements)
Point sources
- Public sewerage	0.16	0.5
- Industrial	1.56	4.9
- Animal husbandry	3.81	12.0
- Fish culture	2.40	7.6
Total	31.74	100

 

J3 SANITARY FACILITIES AND SEWERAGE (Q)

• Percentage of population in the catchment area provided with public

sewerage: 18%.
• Municipal wastewater treatment systems

No. of tertiary treatment systems: 2 (activated sludge). No. of secondary treatment systems: 3 (activated sludge). Rate of treatment: 23,000 m3 day-1.

 

K. IMPROVEMENT WORKS IN THE LAKE (Q)

Kl RESTORATION

Dredging work is being carried out in the lake (100,000 ton yr-1) and at estuaries of main inflowing rivers.

K3 OTHERS

Waters from Naka River and Tone River will be led into Lake Kasumigaura for purifying lake water from 1993 onward.

 

L. DEVELOPMENT PLANS (Q, 3)

    Tsukuba Research Complex has been developed within the lake's catchment area under the support by Japanese Government, Housing and Urban Development Corporation and etc. since 1963 to concentrate national experiment stations and research institutes in a metropolis. The area of the complex is 2,700 ha and the total cost of this plan is about 1,500 billion yen.

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) The Ibaraki Prefectural Eutrophication Prevention Act (1981)
    (2)    Law Concerning Special Measures for Improving Riverhead Areas (1973)
    (3)    Law Concerning Special Measured for Preserving Lake Water Quality (1984)
    * Responsible authorities
    (1)    Ibaraki Prefectural Government
    (2) and (3) National Government
    * Main items of control
    (1)    Water Quality (P, N)
    (3)    Water Quality (COD)

M2    INSTITUTIONAL MEASURES
    (1)    Kasumigaura Section, Bureau of Environmental Protection, Ibaraki Prefectural Government, Mito (Established in 1980)
    (2)    Lake Kasumigaura Work Office, Ministry of Construction, Itako (established in 1967)
    (3)    The National Institute for Environmental Studies, Tsukuba (established in 1974)
 
M3    RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES
    (1)    The National Institute for Environmental Studies
    (2)    Public Works Research Institute, Ministry of Construction
    (3)    Tsukuba University
    (4)    Ibaraki University

    N.    SOURCES OF DATA
 
    *Printed in Japanese. The titles are tentatively translated into English with the original titles in romanized Japanese in parentheses.
    ** In Japanese with English summary.
(Q)    Questionnaire filled by Ibaraki Prefectural Government.
(1)    Japan Map Center (ed.) 1982    Maps of Japanese Lakes (Nihon no Kosho Zushu). Technical Data D1-No.221, Geogr. Survey Inst., Ministry of Construction, Tsukuba.*
(2)    Uchida, E., Asakura, T. & Kawamura, T. (ed.) (1983) Handbook of Japanese Weather Vol.2 (Nihon Kisho Soran, Gekan). 1060 pp. Toyo Keizai Shinposha, Tokyo. *
(3)    Ibaraki Prefectural Government (1979) Report of Lake Survey (Kosho Chosa Hokokusho). 78pp, Mito. *
(4)    Lake Kasumigaura Work Office, Ministry of Construction (1980) Organisms in Lake Kasumigaura (Kasumigaura no Seibutsu). 174pp, Itako.*
(5)    Environment Agency (1981)    The 2nd National Survey on the Natural Environment (Vegetation); Actual Vegetation Map, Ibaraki (Dai-2-Kai Shizen-Kankyo Hozen Kiso-chosa (Shokusei chosa); Genzon Shokusei-zu, Ibaraki-ken). Japan Wildlife Institut, Tokyo. *
(6)    Aizaki, M., Fukushima, T., Ebise, S., Hozomi, M., Iwakuma, T., Hanazato, T., Takamura, N., Nohara, S., Otski, A., Kawai, M., Shiraishi, H. & Nojiri, Y. (1988) Limnological Data in Lake Kasumigaura (Kokuritsu Kogai Kenkyusho Chosa Shiryo). B-33: 1-18. *
(7)    Takamura. N., Iwakuma, T. & Yasuno, M. (1984) The biomass and production of phytoplankton in Lake Kasumigaura during 1981-83. Res. Rep. Natl. Inst. Environ. Stud. Jun., 51: 11-56.**
(8)    Statistics and Information Department, Economic Affairs Bureau, Japanese Ministry of Agriculture and Forestry (1986)    Annual Report on Agriculture, Forestry and Fisheries Statistics (Norin Suisan Tokei Nenpo). Tokyo.*
(9)    Takamura, N., Iwakura, T. & Yasuno, M. (1987) Primary production in Lake Kasumigaura, 1981-1985. Jap J. Limnol., 48 (Special Issue): S13-38.
(10)    Kasuga, S. (1987) Water Quality management through biomanipulation (Kosho no Dobutsuso-Kanri ni yoru Suishitsu-Hozen). Journal of Environmental Pollution Control (Kogai to Taisaku),23:857-863.*