Women “Soap Movement” against Freshwater Red Tide by Uroglena Americana in Lake Biwa, Shiga, Japan

A women-led movement against water pollution, red tides, eutrophication, moved administrators and companies while changing Japanese society.


Due to population growth and factories' settlements resulted from high growth, in the Shiga Prefecture, the water quality deterioration of Lake Biwa, the largest lake in Japan, had come to be regarded as a problem since late 1960[1].  Meanwhile, on 27 May 1977[2], a large scale freshwater red tide was generated by the golden alga Uroglena Americana[3] in the lake[4]. Red tides had occurred before locally[2]. However, at this time the impact was incomparable[2]. The red tide appeared on Lake North and Lake West, which were thought to be cleansed by the citizens of the prefecture[2].  

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Basic Data
NameWomen “Soap Movement” against Freshwater Red Tide by Uroglena Americana in Lake Biwa, Shiga, Japan
ProvinceShiga Prefecture
SiteTakashima-shi, Nagahama-shi, Hikone-shi, Ōtsu-shi, Oumihatiman-shi, Maibarashi, Yasu-shi, Kusatsu-shi, Moriyama-shi, Higashioumi-shi
Accuracy of LocationMEDIUM regional level
Source of Conflict
Type of Conflict (1st level)Industrial and Utilities conflicts
Type of Conflict (2nd level)Chemical industries
Water treatment and access to sanitation (access to sewage)
Aquaculture and fisheries
Specific CommoditiesPhosphorus, Nitrogen
Chemical products
Project Details and Actors
Project DetailsPopulation of the Shiga prefecture in 1977: 1,000,000 [9]

Population of the Kinki area in 1977: 14,500,000 [10]

The transparency of Lake North was 8 to 10m until the 1920s, but then gradually decreased to 4 to 6m around 2000. In Lake South it as only 2m.

The concentration of nitrates at 1m above the bottom of the lake at 80m depth on the Takashima Hikone line of Lake North increased from 0.05 mg/L at the end of the 1950s to 0.26mg/l in the 1990s. The total phosphorus concentration of the water column in Lake North was continuously recorded from 1963 to 1981. Based on this result, it was estimated that the total phosphorus content in the lake increased at a rate of 7.0t/year during this time. [11]

A freshwater red tide in Lake Biwa was observed for the first time in 1977, reaching the highest number of days of occurrence in 1979 (17 days) and the total number of water areas in 1978 (88 water areas). After 1979, both, days of occurrence and total water areas have tended to decrease, and the red tide has not occurred in some years. [12]

In 1977, when a large amount of red tides was generated, the powder soap usage rate was about 10% (estimated by the Shiga Prefecture). Yet, due to efforts by the residents to promote the use of powder soap, two years later, in 1979, the number of people using only powder soap increased by 26%, and those using primarily powder soap increased by 28.1%. In 1980, when the Lake Biwa Ordinance, created by the movement of the residents, was enacted, those who used only powder soap reached 70.6% of the total. In the following year, the enforcement of the ordinance Lake Biwa, the rate of powder soap use dropped sharply to 55.3%, to 49.2% in the following year, and by 20% two years later. After, it continued to decrease gradually, and fell under 40% in 1987 and to about 30%. [13]

Regarding the number of civic organizations in the Prefecture to promote the usage of powder soap to protect Lake Biwa, at the establishment of a general meeting (1978), there were 96 groups, of which some 80 groups represented by women's groups, consumer groups, and businesses such as soap retailers and life promotion councils of 16 municipalities of the Shiga area. In 1988, among the activities of the "Political promotion project to protect the water environment" of the prefectural government, the living promotion councils were established in all the former 50 municipalities. As a result, the number of constituent groups of the meeting increased to 137. However, it began to decrease.gradually. At the time of the general meeting of dissolution on 27 May, 2008, the number of constituent groups of the meeting had decreased to 86 groups including 26 life promotion councils (Note: in Shiga Prefecture in the year 2004, the number of municipalities were reduced from 50 to 26 municipalities after a municipal merger). [14]

Although at the second paragraph of (1) below the figure in p.529 of ref. [15], it is said that "As fund for maintenance of drainage processing facility necessary for drainage standard adaptation, prefecture prepared special loan system for small and medium-size enterprises, but the loan balance of this at the end of March 1958 was 1,510 million yen" (about USD 13,500,000.00). We do not recognize this as project investment.
Project Area (in hectares)67,000
Level of Investment (in USD)n.a.
Type of PopulationSemi-urban
Potential Affected Population1,000,000 - 14,500,000
Start Date27/05/1977
End Date27/05/2008
Company Names or State EnterprisesKao Corporation (Kao) from Japan - Release of phosphorus-free detergent "Just Powder" in March 1980 [17]
Lion Corporation (Lion) from Japan - Lion launched the industry's first non-phosphorus detergent “Seseragi” in the fall of 1973, and has continued to work on reducing phosphorus, and in 1977, completed the reduction of small concentrated phosphorus. [17]
Relevant government actorsShiga prefecture
Environmental justice organisations and other supporters-Shiga Area Women's Groups' Association: http://shigawoman.jp/

-Shiga Area Council Housewife Liaison Committee: http://www.syohisyanet-shiga.jp/link3.html

-Ōtsu Co-op: https://www.pak2.com/index.html
The Conflict and the Mobilization
Intensity of Conflict (at highest level)MEDIUM (street protests, visible mobilization)
When did the mobilization beginIn REACTION to the implementation (during construction or operation)
Groups MobilizingLocal government/political parties
Social movements
Consumer groups, co-ops
Forms of MobilizationCommunity-based participative research (popular epidemiology studies, etc..)
Creation of alternative reports/knowledge
Development of a network/collective action
Development of alternative proposals
Involvement of national and international NGOs
Official complaint letters and petitions
Public campaigns
Shareholder/financial activism.
Street protest/marches
Boycotts of companies-products
Going around, Demonstration (education), On-site inspection
Environmental ImpactsVisible: Biodiversity loss (wildlife, agro-diversity), Loss of landscape/aesthetic degradation, Deforestation and loss of vegetation cover, Surface water pollution / Decreasing water (physico-chemical, biological) quality, Other Environmental impacts
Potential: Food insecurity (crop damage), Soil contamination, Groundwater pollution or depletion, Large-scale disturbance of hydro and geological systems
OtherOffensive odor
Socio-economic ImpactsVisible: Loss of landscape/sense of place
Project StatusIn operation
Pathways for conflict outcome / responseEnvironmental improvements, rehabilitation/restoration of area
Institutional changes
New legislation
Strengthening of participation
Technical solutions to improve resource supply/quality/distribution
Application of existing regulations
New Environmental Impact Assessment/Study
Withdrawal of company/investment
Do you consider this as a success?Yes
Why? Explain briefly.The movement by local women forced the administration to the point of prohibiting the production and sale of the product that caused the red tides: the spread of this trend to the whole country has become significant for the lives of people.
Sources and Materials

Mother Lake 21 Project (accessed on 19-03-2019)
[click to view]

The regulations about prevention of eutrophication of Lake Biwa of Shiga Prefecture (accessed on 19-03-2019)
[click to view]


[14] Chapter 4: Social network analysis for Lake Biwa meeting (accessed on 25-03-2019)
[click to view]

[2] Chapter 2: Transition of the environment conservation movement in Shiga prefecture and soap movement (accessed on 25-03-2019)
[click to view]

[11] Muneta Y. (2 Jun. 2008). Eutrophication and Hypoxia of Lake Biwa. Institute for Chemical Research, Kyoto University. (accessed on25-03- 2019)
[click to view]

[13] Chapter 4: What is Soap Movement? (accessed on 25-03-2019)
[click to view]

[12] Chapter 3: Water quality of Lake Biwa and Yodogawa water system (accessed on 25-03-2019)
[click to view]

[15] Kotani H., 1984, Water pollution control of Lake Biwa, Feature: Lake Biwa development and environmental protection technology, Vol. 13, No. 7 (accessed on 12-04-2019)
[click to view]

[17] Udou Y., Relationship between entry order and market share in the domestic laundry detergent market (accessed on 12-04-2019)
[click to view]


[5] Shiga prefecture, The 30th anniversary of the Day of Biwako (accessed on 25-03-2019)
[click to view]

[2] Sekken Hyakka (accessed on 25-03-2019)
[click to view]

Lake area (accessed on 25-03-2019)
[click to view]

[6] Kyoto Shinbun "The present soap movement", 17 May 2015 (accessed on 25-03-2019)
[click to view]

[8] Eutrophication problem, Lake Biwa Handbook revised edition (accessed on 25-03-2019)
[click to view]

[10] Nihon Keizai Shinbun "Stop the red tide by Public-Private relationship - Lake Biwa Environment Regeneration Path (1)”, 18 May 2015 (accessed on 25-03-2019)
[click to view]

About Prefecture liaison meeting of civic movement to promote the usage of powder soap to protect Lake Biwa, Paragraph 3 (accessed on 25-03-2019)
[click to view]

Shiga water environment business promotion forum, System design, approach for water environmental preservation of Lake Biwa by administration (accessed on 25-03-2019)
[click to view]

[1] Shiga water environment business promotion forum, Activities of citizens of the prefecture who protect Lake Biwa (accessed on 25-03-2019)
[click to view]

[7] Lake Biwa and human life, Lake Biwa Handbook revised edition (accessed on 25-03-2019)
[click to view]

[3] Freshwater red tide (accessed on 30-03-2019)
[click to view]

[4] About present conditions and problem measures of environmental problems of Lake Biwa (accessed on 30-03-2019)
[click to view]

[9] Shiga prefecture, Population and number of households in Shiga prefecture (accessed on 25-03-2019)
[click to view]

Shiga Prefecture, Overview of Lake Biwa (accessed on 25-03-2019)
[click to view]

[16] Kao (accessed on 12-04-2019)
[click to view]

[18] Lion (accessed on 12-04-2019)
[click to view]

Other Documents

Women were at the center of the soap movement A parade of about 250 people calling for the use of powder soap in a shopping street (April 1979, Ōtsu city)
[click to view]

Soap movement (1970s) aiming to expel synthetic detergent State of soap movement
[click to view]

Lake Biwa simultaneous cleaning, preservation activity of Yoshi community State of Lake Biwa simultaneous cleaning
[click to view]

Citizenship to protect Lake Biwa connected by "Mother Lake Forum" 1 State of Mother Lake Forum
[click to view]

Citizenship to protect Lake Biwa connected by "Mother Lake Forum" 2 State of Mother Lake Forum
[click to view]

Rainwater use Image of rainwater use as one of the current soap movement's activities
[click to view]

Demonstration Demonstration of washing and comparing synthetic detergent and soap using two washing machines
[click to view]

Experience reaping and picking of aquatic plants Experience reaping and picking of aquatic plants that breed well in the water and affect water quality
[click to view]

Release Wataka by children 1 In order to reduce the unusually abandant aquatic plants in South Lake, children release juveniles of an endemic species, Wataka, of the Lake Biwa, which is herbivorous and endagered.
[click to view]

Release Wataka by children 2 In order to reduce the unusually abandant aquatic plants in South Lake, children release juveniles of an endemic species, Wataka, of the Lake Biwa, which is herbivorous and endagered.
[click to view]

Biwako Floating School Biwako Floating School: Learn the importance of touching Lake Biwa and protecting the environment
[click to view]

"Mizuuminoko" water survey using a water tank Observe the transparency by looking from the side of the dial placed in the elongated water tank
[click to view]

Meta Information
ContributorEnvJustice, ICTA-UAB/Natsuka Kuroda,[email protected]
Last update20/04/2019