Lake Biwa and the Soap Movement
After a red tide in 1977, Shiga residents switched to soap, and in 1980 the prefecture limited phosphorus to protect Lake Biwa (Shiga Prefecture).
Image: NASA (ISS007-E-17620, astronaut photograph of Lake Biwa and Shiga Prefecture).
Last reviewed: 1 source cited
Families swapping their detergent for soap helped change the law for Japan's biggest lake.
Around Lake Biwa Day each July, more than 100,000 people join cleanups around the lake (Shiga Prefecture).
Source: Shiga Prefecture, Think about life by seeing Lake Biwa
Explain Like I'm 10
- Lake Biwa is the biggest lake in Japan.
- Phosphorus from washing detergent fed tiny algae until the water turned red in 1977.
- People switched to natural soap, and new rules cut the phosphorus going into the lake.
The Five W's of the Soap Movement
Who
The people of Shiga, whose citizen movement led Shiga Prefecture to act.
Source: Shiga Prefecture, Think about life by seeing Lake Biwa
What
The Soap Movement, then the Ordinance for the Prevention of Eutrophication of Lake Biwa.
Source: Shiga Prefecture, Think about life by seeing Lake Biwa
When
A large freshwater red tide in 1977; the ordinance took effect on 1 July 1980, now Lake Biwa Day.
Source: Shiga Prefecture, Think about life by seeing Lake Biwa
Where
Lake Biwa, Shiga Prefecture, Japan.
Source: Shiga Prefecture, Think about life by seeing Lake Biwa
Why
Phosphorus from detergents was feeding excessive growth of Tiny plant-like living things that drift in water and use sunlight to make food. They make much of the oxygen we breathe and feed ocean life. Glossary in the lake.
Source: Shiga Prefecture, Think about life by seeing Lake Biwa
Connected Solutions
- Lake Constance Phosphorus Recovery Another lake saved by cutting phosphorus.
Impact Statement
Community and government solution · active
The citizen movement led directly to a prefecture law limiting phosphorus, and every 1 July is now Lake Biwa Day (Shiga Prefecture).
Source: Shiga Prefecture, Think about life by seeing Lake Biwa
For Further Information: Shiga Prefecture, Think about life by seeing Lake Biwa
Shiga shares what it learned at Lake Biwa with places facing similar lake problems around the world (Shiga Prefecture).
How This Saves People & the Planet
For People
Residents meet every year to exchange ideas and cheer on efforts for the lake (Shiga Prefecture).
Source: Shiga Prefecture, Think about life by seeing Lake Biwa
For Nature
Ongoing work also removes invasive alien species that threaten native species in and around the lake (Shiga Prefecture).
Source: Shiga Prefecture, Think about life by seeing Lake Biwa
Learn More About Lake Biwa
Want to go deeper? Shiga Prefecture tells the story.
For Further InformationRelated Solutions
More solutions like this one, matched by meaning.
Help This Work
Links go straight to the organization. Saving Planets doesn't receive any of the money.