KAWAGUCHI-KO (LAKE KAWAGUCHI)

Mt. Fuji and the lake


Photo: A. Kurata

A. LOCATION

• Yamanashi Prefecture, Japan.


• 35:31N, 138:45E; 832 m above sea level.

B. DESCRIPTION

Lake Kawaguchi is one of the five lakes surrounding Mt. Fuji. These lakes were formed as a result of barrage formation by volcanic debris and solidified magma spewed out of Mt. Fuji and the off-spring volcanic outlets nearby. The lake is the oldest of the five and it is at least 50-60 thousand years old. There are scores of underwater springs at the lake bottom. There is no discernible surface flow into or out of the lake. Major flows of water appear to take place underground. In 1912 a sluiceway was constructed to discharge a maximum flow of 7.79 m3 sec-1 (named Usobuki River). Artificial regulation of flow has been made possible by flow augmentation from Lake Sai, one of the remaining four lakes, for supplementing water for power generation. The number of visitors to the five-lake area exceeds ten million annually. Lake Kawaguchi, directly linked to Tokyo Metropolitan urban districts through a major artery highway and closest to the terminal of the Fuji Subaru scenic route, is a centre of tourist attraction in this area.
The transparency of the lake was 4-7 m some 60 years ago, but the 1972 measurement indicated only 3-4 m. A regional sewerage project was initiated in 1974 and the provision of service to portion of the area has begun in 1986 (Q).

C. PHYSICAL DIMENSIONS

Surface area [km2]	6 (1)
Volume [km3]	0.0555 (1)
Maximum depth [m]	16.1 (1)
Mean depth [m]	9.3 (1)
Water level	Regulated
Normal range of annual water
- level fluctuation [m]	2-3 (2)
Length of shoreline [km]	20.9 (3)
Residence time [yr]	0.3 (4)
Catchment area [km2]	120 (5)

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL (Q)

• Bathymetric map: Fig. ASI-25-01.


• Names of main islands: Uno-shima.


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

D2 CLIMATlC (6)

• Climatic data at Kawaguchi-ko, 1951-1980

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Ann.
Mean temp. [deg C]	-1.2	-0.4	2.9	8.8	13.3	16.9	20.9	21.6	17.7	11.7	6.8	1.7	10.6
Precipitation [mm]	53	62	87	115	129	182	171	205	209	165	79	51	1,506

• Number of hours of bright sunshine: 2,040 hr yr-1.


• Snowfall: 0.33 m.

Fig. ASI-25-01
Bathymetric map (Q).

• Water temperature [deg C](Q)

Station 1, 1981-1985
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0.3	4.0	4.6	6.5	14.4	17.9	20.6	23.9	24.6	20.7	15.7	11.9	7.5

• Freezing period: January-March (Q).


• Mixing type: Dimictic (Q).

E. LAKE WATER QUALITY (Q)

E1 TRANSPARENCY [m]

Station 1, 1981-1985
	Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
		3.6	3.7	3.5	2.9	3.3	3.0	2.8	2.4	2.8	2.2	2.6	3.0

E2 pH

Station 1, 1981-1985
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0.3	7.6	7.5	7.6	7.9	8.1	8.5	8.7	8.3	7.9	7.6	7.7	7.6

E3 SS [mg l-1]

Station 1, 1981-1985
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0.3	1.6	2.1	1.7	2.2	2.0	1.8	2.0	4.2	1.9	3.3	2.7	2.3

E4 DO [mg l-1]

Station 1, 1981-1985
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0.3	11.5	11.1	11.1	10.2	9.6	9.7	9.1	8.2	8.1	8.2	9.2	10.0

E5 COD [mg l-1]

Station 1, 1981-1985
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0.3	3.1	2.9	2.8	2.9	3.6	3.5	3.4	3.8	3.1	2.9	2.9	2.9

E6 CHLOROPHYLL CONCENTRATION [micro l-1]

Station 1, 1981-1985
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0.3	-	-	-	-	6.6	-	7.4	7.1	-	-	8.2	-

E7 NITROGEN CONCENTRATION

• Total-N [mg l-1]

Station 1, 1981-1985
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0.3	0.57	0.46	0.38	0.37	0.44	0.34	0.34	0.52	0.44	0.50	0.49	0.45

E8 PHOSPHORUS CONCENTRATION

• Total-P [mg l-1]

Station 1, 1981-1985
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0.3	.012	.010	.011	.09	.011	.017	.012	.018	.017	.013	.013	.012

E10 PAST TRENDS: Fig. ASI-25-02 and 03.

Fig. ASI-25-02
Past trend of transparency at Station 1.

Fig. ASI-25-03
Past trends of total nitrogen and total phosphorus.

F. BIOLOGICAL FEATURES

F1 FLORA

• Phytoplankton (7)
  Anabaena solitaria f. planctonica, Melosira crenulata, M. granulata, Fragilaria erotonensis, Synedra ulna, Mougeotia sp.

F2 FAUNA

• Zooplankton (8)
  Ploesoma hudsoni, P. truncatum, Bosminopsis deitersi, Bosmina longirostris.
• Benthos (3, 9)
  Chironomus fujitertius, Glyptotendipes tokunagai, Pentapedilum sordens, Tanytarsus oyamai.
• Fish (10)
  Hypomessus olidus*, Cyprinus carpio*, Carassius langsdorfi*, Anguilla japonica, Zacco platypus, Tribolodon hakonensis hakonensis. * Economically important.

F3 PRIMARY PRODUCTION RATE [g O2 m-2 day-1](Q)

Station 1, 1981
	Jul
Net production	3.23
Dark respiration	0.98
Gross production	4.21

F5 FISHERY PRODUCTS (10)

• Annual fish catch [metric tons]
  1982: 24.

F7 NOTES ON THE REMARKABLE CHANGES OF BIOTA IN THE LAKE IN RECENT YEARS (Q)

Population of Japanese smelt (Hypomessus olidus) decreased in 1985 and 1986. Large-mouth bass (Micropterus salmoides) increased in recent years.

G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA (Q)

1984
	Area [km2]	[%]
Natural landscape
- Woody vegetation	96.2	79.9
- Herbaceous vegetation	1.1	0.9
Agricultural land	6.8	5.6
Residential area	8.5	7.1
Others	7.8	6.5
Total	120.4	100

• Main types of woody vegetation (11)
  Evergreen conifer forest (Abies homolepis, A. veitchii, Tsuga diversifolia, Pinus densiflora); deciduous broadleaf forest (Quercus spp., Castanea crenata, Betula ermanii); evergreen and deciduous conifer plantation (Larix kaempferi, Pinus densiflora, Abies homolepis).
• Types of important herbaceous vegetation: Grassland and weeds (11).


• Main kinds of crops: Vegetables, maize (12).


• Levels of fertilizer application on crop fields: Moderate (Q).

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

1980
	Gross product per year [mill. yen]	No. of persons engaged	No.of establishments
Primary industry 10
- Crop production &
- Animal husbandry	1,130
- Fisheries	12
- Others	53
Secondary industry	400	2,710	353
Tertiary industry	202	6,096	1,481

• Numbers of domestic animals in the catchment area
  Cattle 320, swine 221, poultry 33,400.

G3 POPULATION IN THE CATCHMENT AREA (Q)

1985
	Population	Population density [km-2]	Major cities (population)
Rural	20,654	-
Total	20,654	171.5

H. LAKE UTILIZATION (Q)

H1 LAKE UTILIZATION

Source of water, sightseeing and tourism (no. of visitors in 1983: 5,140,000), recreation (sport-fishing) and fisheries.

H2 THE LAKE AS WATER RESOURCE

	Use rate [m3 sec-1]
Irrigation	2.53

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS (Q)

I1 ENHANCED SILTATION

• Extent of damage: None.

I2 TOXIC CONTAMINATION

• Present status: None.

I3 EUTROPHICATION

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

1975
Sources	Industrial	Domestic	Agricultural	Natural	Total
T-N	2.1	50.7	24.2	48.3	125.3
T-P	0.1	10.5	4.3	1.3	16.2

• Supplementary notes
  The annual means of measurements for a period between 1982-1985 were 2.6-3.4 m for transparency, 4.08-9.92.micro g l-1 for chlorophyll a, 0.35-0.56 mg l-1 for total nitrogen, and 0.011-0.016 mg l-1 for total phosphorus, indicating a trend from mesotrophic to eutrophic state. The Lake Kawaguchi Water Quality Protection Committee was formed by the municipalities concerned and it has been undertaking collaborative water quality management activities, including the promotion of the use of grey-water solid separation units. A local sewerage project has also been undertaken in Yamanashi Prefecture for part of the northern slope of Mt. Fuji.

I4 ACIDIFICATION

• Extent of damage: None.

J. WASTEWATER TREATMENTS (Q)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA

b) No sources of significant pollution.

J2 APPROXIMATE PERCENTAGE DISTRIBUTION OF POLLUTANT LOADS

	[%]
Forests	8.8
Agricultural fields	19.7
Households	42.7
Tourists	16.9
Livestock	12.5
Total	100

J3 SANITARY FACILITlES AND SEWERAGE

• Percentage of rural population with adequate sanitary facilities (on-site
  treatment systems): 39%.
• Industrial wastewater treatment systems
  No. of industrial wastewater treatment systems: 40 (biological treatment).

K. IMPROVEMENT WORKS IN THE LAKE (Q)

K1 RESTORATION

Sewerage discharge has been diverted from the catchment area.

L. DEVELOPMENT PLANS (Q)

A sight-seeing highway (Subaru Line) was constructed in 1961-1964 by Yamanashi Prefectural Government (cost: 1,700,000,000 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. Yamanashi Prefecture Anti-Pollution Ordinance
2. Lake Kawaguchi Grey Water Regulation Ordinance
• Responsible authorities


1. Yamanashi Prefecture
2. Kawaguchi-ko Town
• Main items of control


1. Establishment of locally pertinent effluent standards
2. Promotion of the use of household grey-water solid separation units

M2 INSTITUTIONAL MEASURES

1. Monitoring and regulatory measures; Environmental Protection Section, Livelihood Division, Yamanashi Prefectural Government

M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES

1. Yamanashi Prefectural Institute of Public Health and Anti-pollution

N. SOURCES OF DATA

17. Questionnaire filled by Economic Welfare Bureau, Environmental Protection Section, Yamanashi Prefectural Government.
1. Shimizu, G. (1980) Annual Report of the Yamanashi Institute for Public Health and Antipollution (Yamanashi-ken Eisei Kogai Kenkyu-sho Nenpo), 24: 30-32.*
2. Kasai et al. (1976) Journal of Water and Waste (Yosui to Haisui), 18: 25.*
3. Geographical Survey Institute, (1975) Lake shoreline Statistics (Kogansen Shukei-hyo) Digital National Land Information (Kokudo Suchi Joho).
4. Yamanashi Prefectural Government (1984) Survey on Limnological Aspects of the Lakes (Kosho no Shogen ni kansuru Chosa), Kofu.*
5. Land Bureau, National Land Agency (1982) Water Usage Map of Yamanashi Shizuoka Regional Watersystems (Yamanashi-Shizuoka Chiiki Shuyo Suikei Risui Genkyo Zu), Kofu.*
6. Kofu Regional Meteorological Station (1982) Tables of Climatic Data in Yamanashi Prefecture (Yamanashi-ken Kisho Heinenchi Hyo), Kofu.*
7. Yamanashi, T., Oshima, K. & Watanabe, M. (1982) Memoirs of the National Science Museum (Kokuritsu Kagaku Hakubutsu-kan Senpo), 15: 91-97.*
8. Yoshida, Suginome & Tanaka, (1974) Bulletin of Freshwater Fisheries Research Laboratory (Tansui-ku Suisan Kenkyu-sho Kenkyu Hokoku), 24 (1): 1-9.*
9. Sasa, M. (1985) Research Report from the National Institute for Environmental Studies, Japan, 83: 106-160.
10. Fish Hatchery Centre of Yamanashi Prefecture.
11. Yamanashi Prefectural Government (1977) Vegetation Map of Yamanashi Prefecture (Yamanashi-ken Shokusei-zu), Kofu.*
12. Yamanashi Prefectural Government (1986) Yamanashi Prefectural Annual Statistics (Yamanashi-ken Tokei Nenkan), Kofu.*

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