Pollution of the Yamato River, Japan

Yamato River was one of the dirtiest rivers in Japan with excessive BOD in the 1970s. After a series of recovery policies and actions, sweetfish ( "ayu") returned to the river in the 2000s.


The Yamato River used to be a familiar river widely known as a place of river play until the 1950s.  However, along with the high economic growth, the development of the watershed developed as a residential area in the Keihanshin metropolitan area.  When the industry was concentrated, the water quality deteriorated sharply due to household drainage, factory drainage, and livestock drainage.  Since the 1960s, the Yamato River's water quality had a poor condition making it unsuitable for the use of water and other hydrophilic and living creatures.  70% of the causes of pollution in the Yamato River were domestic wastewater. At that time, the sewerage coverage rate of households in the Yamato River basin was less than 20%. This means that domestic drainage flowed into the river without any treatment [1].

See more...
Basic Data
NamePollution of the Yamato River, Japan
ProvinceOsaka and Nara
SiteOsaka, Sakai, Yao, Nara, Yamatotakada, Yamatokōriyama
Accuracy of LocationMEDIUM regional level
Source of Conflict
Type of Conflict (1st level)Water Management
Type of Conflict (2nd level)Water access rights and entitlements
Landfills, toxic waste treatment, uncontrolled dump sites
Urban development conflicts
Aquaculture and fisheries
Specific CommoditiesWater
Industrial waste
Domestic municipal waste
Project Details and Actors
Project DetailsYamato River is about 68 kilometers in length. [8]

The population in the Yamato River basin in Nara and Osaka Prefectures was less than 1 million until the 1950s while it reached 2 million during the 1980s. [1]

Approx. 85% of Nara Prefecture's population is concentrated in the Yamato River basin. [4]

It is currently used as drinking water in 10 municipalities in Osaka and Nara prefectures. [6]

The sewerage penetration rate in the Yamato River basin continued to fall below the national average until 2001. It was 86.9% in 2015, exceeding the national average of 77.8%. [1]

Approx. 70% of the causes of soiling in 2013 were “living wastewater”, following factories, etc. (13.2%), livestock (10.1%), and nature (3.9%). [1]

The Yamato River basin is characterized by annual precipitation less than the national average and less water flowing into the river. Therefore, the river is particularly polluted in winter (December-February) when the amount of water decreases. [1]

As for the water quality of the Yamato River, the average water quality (BOD 75% value) at eight locations in the main river was 11.6 mg/l. [4] Although it fell below the environmental standard (5 mg/l) for the first time in 2004, BOD values continued to exceed 5 mg/l for several years starting in 2005. However, since 2008, the main river has continued to fulfill the environmental standard, and it fell to BOD value 2.3mg/l in 2015. [1]

Measurements were done in the spring of 2004 on the elements contained in the "otoliths" of three sweetfish collected in the lower Yamato River and on 15 sweetfish collected in the vicinity of Kawachi Bridge in the spring of 2005. It turned out that all of them are natural sweetfish which swam up, testifying to increased quality of the water. [5]

The Yamato River is one of the many rivers in Japan where "cormorant fishing" was practiced. The birds are roped together and the fishermen tie string around each one’s throat to stop them eating the fish they catch. The practice has been in decline, and nowadays attracts tourists.

Project Area (in hectares)107,000
Type of PopulationSemi-urban
Potential Affected Population2,000,000
Start Date1960
End Date2009
Relevant government actors-Ministry of Land, Infrastructure, Transport and Tourism Kinki -Regional Development Bureau, Yamato River river office

-Osaka Prefectural Government

-Nara Prefecture

-Matsubara city
International and Financial InstitutionsLions Club from United States of America - They preside over Yamato River water quality improvement activity.
Environmental justice organisations and other supporters-Yamato River Clean Flow Revival Network (http://yamato-river.net/index.html)

-Yamato River Natural Sweetfish Study Group

-Kashiwara E-net (https://kashiwara-e.net/)
The Conflict and the Mobilization
Intensity of Conflict (at highest level)MEDIUM (street protests, visible mobilization)
When did the mobilization beginMobilization for reparations once impacts have been felt
Groups MobilizingLocal government/political parties
Recreational users
Local scientists/professionals
Fisher people
Forms of MobilizationCommunity-based participative research (popular epidemiology studies, etc..)
Development of a network/collective action
Involvement of national and international NGOs
Public campaigns
Appeals/recourse to economic valuation of the environment
Research and administrative guidance; Setting administrative goals; Facility maintenance
Environmental ImpactsVisible: Biodiversity loss (wildlife, agro-diversity), Loss of landscape/aesthetic degradation, Surface water pollution / Decreasing water (physico-chemical, biological) quality
Potential: Food insecurity (crop damage), Soil contamination, Waste overflow, Oil spills, Groundwater pollution or depletion, Large-scale disturbance of hydro and geological systems, Reduced ecological / hydrological connectivity
Health ImpactsVisible: Accidents
Socio-economic ImpactsVisible: Loss of traditional knowledge/practices/cultures, 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
Application of existing regulations
Do you consider this as a success?Not Sure
Why? Explain briefly.Improvement of water quality standards alone is not enough for the restoration of biodiversity. There are still many issues to be improved in order to realize the potentiality of the river as habitat, growth spawning, and hatching of more aquatic life [12].

It is considered extremely important to deepen the understanding and to strengthen the cooperation of various stakeholders in these areas and to make it an approach in the whole basin area [12].
Sources and Materials

Water environment improvement emergency plan (accessed on 12-04-2019)
[click to view]

Second Phase Water Environment Improvement Emergency Action Plan (accessed on 12-04-2019)
[click to view]

C Project Plan 2006 (Water Environment) (accessed on 12-04-2019)
[click to view]

Yamato River water environment improvement plan (accessed on 12-04-2019)
[click to view]


[3] Yamamoto K. and Inoue H., Consideration on environmental improvement of river based on water quality survey of Hatsuse River (the Yamato River basin), Research note (accessed on 10-04-2019)
[click to view]

[2] Ueno H. et al, 2012, Confirmation of natural upswimming using otolith Sr/Ca ratio of sweetfish of Yamato River, Bulletin of Osaka University of Education, Third Division, Volume 61, 17-21, (accessed on 10-04-2019)
[click to view]

[10] Nagata Y., River maintenance fund furtherance business, "Mass runaway program of natural sweetfish in the urban river" Yamato River "", Achievement report (accessed on 12-04-2019)
[click to view]

Yoshiaki Tsuzuki & Minoru Yoneda, 2011, Pollutant runoff yields in the Yamato-gawa River, Japan, to be applied for EAH books of municipal wastewater intending pollutant discharge reduction

Journal of Hydrology 400(3-4):465-476.
[click to view]


[6] Miyatake et al., Water quality pollution in Osaka bay, Group 1 (accessed on 10-04-2019)
[click to view]

[7] Osaka Prefectural Government, Make Yamato River Cleaner! (accessed on 10-04-2019)
[click to view]

[8] Sankei West, 6 April 2014, "Japan's dirtiest river = Yamatogawa" is reviving ... Figures of wild birds, figures of fish, and water quality improvement (accessed on 10-04-2019)
[click to view]

Yamato River water system (accessed on 12-04-2019)
[click to view]

Reason why Yamatogawa is dirty (accessed on 12-04-2019)
[click to view]

Eco Nara, Water pollution problem of Yamato River (accessed on 12-04-2019)
[click to view]

[1] River office of Yamato River, Ministry of Land, Infrastructure, Transport and Tourism Kinki Regional Development Bureau, Water environment of Yamato River - For improvement of water environment (accessed on 10-04-2019)
[click to view]

Yamatogawa Integrated Watershed Environment Improvement Project Evaluation
[click to view]

History of Yamato River
[click to view]

[9] Lions Club
[click to view]

[5] Kashiwara E-net, 20 August 2012, Sweetfish has backed to Yamato River (accessed on 10-04-2019)
[click to view]

Sweetfish has returned to Yamato River! (accessed on 12-04-2019)
[click to view]

[4] Yamato River Fresh Stream Revival Network, Revive! The Yamato River CFresh Stream Revival Project (accessed on 10-04-2019)
[click to view]

Other Documents

State of the river since the 1970s (2) The water quality significantly deteriorated due to household drainage, rubbish and manure.
[click to view]

Children playing with water In the 1960s, many children used to be playing in the river.
[click to view]

Dead fish Many water quality accidents occur in the Yamato River water system.
[click to view]

Sweetfish's upstream In recent years, spawning of natural sweetfish and juvenile sweetfish have been confirmed annually downstream.
[click to view]

Collected sweetfish Collected sweetfish by Emeritus Professor Yoshikazu Nagata, Osaka University of Education
[click to view]

Otolith Otolith
[click to view]

Children playing with water By the 1960s, many children used to be playing in the river.
[click to view]

Yamato River Waterside Festival Every year since 2006, the waterside event takes place downstream, and the children enjoy water play.
[click to view]

Oil fence to prevent oil spill Related organizations cooperate and store oil fences and adsorption mats to prevent the spread of oil downstream and the spread of damage in river offices, civil engineering offices, municipalities, etc., and prepare for emergency response.
[click to view]

Kashiwara dam and fish path You can see the Kashiwara dam in the back. There is a new fishway in front.
[click to view]

Sumiyoshi Taisha's The Sumiyoshi Taisha's God Passage, which carries the shrine and crosses the Yamato River, was revived for the first time in 41 years in 2004.
[click to view]

Meta Information
ContributorEnvJustice, ICTA-UAB/Natsuka Kuroda, [email protected]
Last update08/05/2019