CaseYodo River Basin Management Structure

Water utility

Osaka Water Supply Authority

General information of the utility (2019) *(w) represents data of wholesale water supply
OperationtypePublic(wholesale & retail supply)Service area (km2)－Population
served－Distribution (m3/d)

1,487,610（w）

Servicecoverage(%)－

Pipe length (km)（w）

NRW (%)

0%（w）

Number of staff547

Number ofwater sources
Water rates(JPY)

Surface water (3), Groundwater (0), Others (0)－(in case of 10m3 of water use per month forresidential customers)

Summary

The Yodo River is the source of water supply for the Osaka Water SupplyAuthority (Authority). The river is constantly under threat of water pollution
incidents due to oil and harmful substances, and depending on the nature andscale of water pollution, water intake might get suspended. Therefore, inaddition to continuous raw water monitoring, the Authority has acollaborative structure in place to address sudden changes in water quality
through close cooperation with related agencies and organizations in the YodoRiver basin.

Current Status& Challenges

Primarily fed by Lake Biwa and joined by three rivers which are Uji, Kizu,and Katsura, the Yodo River has a relatively stable flow conditions ascompared with other rivers in Japan and is a source of water supply for
approximately 12 million people in the basin (Figure 1).
It is a "repeatedly used river" that flows through various urban areas and isconstantly exposed to the threat of water pollution incidents due to oil andharmful substances. Therefore, depending on the nature and scale of waterpollution, water intake might need to be suspended.

Yodo River Basin
Yodo River Supply Area
Prefectural BorderGifu
Pref.

Fukui
Pref.

Kyoto
Pref.

a e iwa

Katsura River
yogoPref.

Shiga Pref.

Uji River
InaRiverKizu Rivero o i er

Osaka Pref.

MiePref.

Osaka Bay

NaraPref.

Figure 1 | Lake Biwa-Yodo River basin(http://www.byq.or.jp/kankyo/k_01.html)

Measures &Solutions

1. Monitoring of raw water quality at the Authority
Of the tap water supplied by the Authority to all of Osaka Prefecture(excluding Osaka City), about 80% is supplied by the Murano Water Treatment
Plant, which takes its raw water from the Yodo River at the Isojima Intake Plant
which is approximately 4 km away from the treatment plant.
To supply safe and high-quality tap water, the Authority regularly monitors
water sources including the Lake Biwa and Yodo River and tests their raw
water quality daily. The Authority also conducts continuous monitoring of raw
water at the Isoshima Intake Plant using a carp sensor (a device that can early
detect harmful substances through observation of carps behavior) (Figure 2 &3) and a Yuki sensor (a device that monitors 21 raw water components 24/7,
including volatile organic substances such as benzene, which are regulated by
the national drinking water quality standards).

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Figure 2 | Carp sensor

NormalStateWater ow
Pollu onsuspected

Pollution suspected if the number of carps combining No.1, No.2 and No.3
is less than No.5.

Figure 3 | Behavioral pattern of carps
2. Cooperation among elate Organizations in the o o i er asin
The Lake Biwa-Yodo River water system is one of the largest water systems
in Japan, and it is important to take appropriate water quality conservation
measures throughout the entire system. For occasions such as when suddenchanges in raw water quality take pace, for example, it is necessary to work inclose cooperation with relevant agencies and organizations in the basin.
(1) Yodo River Water Pollution Prevention Liaison Council
In 1958, the Yodo River Water Pollution Prevention Liaison Council (Council)
was established to take emergency measures against anomalous water
qualities in the Lake Biwa-Yodo River system. The Council consists of 24
agencies and organizations including the national government, the river’s
upstream and downstream prefectures, and its downstream water utilization
entities.
The objective of the Council is to:• survey the water quality of the rivers and waterways in the Yodo Riversystem and understand their conditions;• clarify the mechanism of water pollution in the Yodo River system, and3 / 5

to conduct research on water quality management methods andpollution prevention measures in the basin; and• improve the water quality of the Yodo River effectively through mutualcommunication and coordination among the council members.
In the event of a water quality incident, the Council members contact witheach other via NTT’s telephone lines and the Ministry of Land, Infrastructure,Transport and Tourism's dedicated telephone lines, in order to swiftly address
the incident.
(2) Yodo River Water Quality Council
In 1965, the Yodo River Water Quality Council (Quality Council) wasestablished, comprised of seven water utilities (currently nine utilities) that
abstract raw water from the Yodo River.
The Quality Council aims to:• monitor and investigate the river’s water quality;• prevent the river’s water pollution by negotiating with andcommunicating related information to the national government andlocal governments upstream of the river;• establish an emergency communication line so that the member
utilities can work together efficiently when sudden water quality
incidents occur; and• conduct public outreach about water quality conservation.
In recent years, the member utilities have conducted a joint survey onradioactive substances (cesium-134, cesium-137, and iodine-131) at five
representative points in the Lake Biwa-Yodo River system, and have publishedits result.
(3) Mutual communication line in the event of water quality incident
Figure 4 shows the basic communication line among the Quality Council
members in the event of a water quality incident in the Yodo River. In addition,
another communication line has also been established to address anomalous
water qualities occurring at the water facilities operated by the Quality
Council members. These communication lines help efficient coordination
among the member utilities and with other relevant agencities andorganizations.

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River’s administrator

Discoverer

Authority

Other Quality
Council members※Communication made by FAX

Figure 4 | Basic communication line in the event of water quality incident

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