Japan Water Agency Incorporated Administrative Agency (JWA)
JWA supplies safe and quality water to meet the demand of people in Japan. To ensure stable supply of such water, JWA works around the clock, 365 days a year, to operate and maintaain its water supply facilities, including dams and canals.
 Stably supplying safe and quality water
Stable water supply (Water supply from dams)
The stream flow changes depending on the rainfall. When it decreases due to poor rainfall, for example, JWA supplies water that has been stored in the dam reservoir to the river downstream so as to ensure that necessary amount of water can be taken stably from the river. JWA also supplies necessary amount of water to facilitate water transportation, fisheries, and conserve the river environment.
Safe and quality water supply
JWA conducts water quality surveys and facility patrols to monitor day-to-day water quality. It also addresses eutrophication and water turbidity with effective use of its facilities. In the event of pipeline leakage or a water quality hazard due to an oil spill in a river or canal, JWA takes prompt action to prevent the damage from spreading and notify water users for information sharing.
 Preventing and mitigating flood hazards
Flood control with dams
Dams perform an important function of storing river water that increases rapidly in volume due to heavy rain and regulate discharges downstream (flood control function). Weirs and barrages raise water levels with their gate shut down in normal times. At the time of flood, however, the gate is opened to allow excessive river water to flow downstream safely. When a heavy rain that may cause floods is expected, JWA accurately assess weather information and streamflows and operate its dams, weirs/barrages, and facilities accordingly.
 Preparing for crises
Better seismic performance
JWA keeps improving the seismic performance of its facilities, thereby enhances public confidence in their security. To this end, JWA checks their performance and assess their risks in relation to major earthquakes. Based on the findings of such checks and assessment, JWA is conducting seismic measures to its facilities systematically.
Routine training for major disasters
JWA works with the central government, water users, the police, fire and disaster management authorities and other institutions concerned to conduct flood response exercises and earthquake and disaster management drills regularly to prepare for floods, major earthquakes and other natural disasters, as well as water quality hazards. JWA also has a stockpile of steel pipes, pump trucks and other equipment and materials in preparation for any contingency on its canal facilities.
 Ensuring facility integrity
Facility inspection and maintenance
JWA works to conserve and manage its facilities through routine patrol, inspection and maintenance. On dam reservoirs, it collects driftwood and solid waste using work boats. JWA also strives to find any malfunction of its canal facilities and leakage from them as early as possible. It promptly repairs any leak from such facilities so that water supply can be smooth without interruptions.
Stock management of canals and other facilities
JWA conducts routine inspection, maintenance and regular functional diagnostic study to accurately assess the state of each facility and share the information on their risks and their effects to water users so as to take necessary measures appropriately to extend the facility life and reduce its life-cycle costs.
Extending the life of dams
To secure the safety and long life of functions of dams, JWA conducts periodical inspections every three years and for the dams with 30 years services since the start of management, JWA implements the comprehensive inspection of each of them. Based on the result of that inspection, it makes the plan to extend the life of the dam, in which a medium and long-term maintenance and management policy of individual facilities comprising the dam is formulated and systematic maintenance and management work for them are carried out.
 Developing facilities in a systematic and appropriate manner
Construction and reconstruction of dams, canals and other facilities
JWA constructs and reconstructs dams, canals and other facilities systematically so that water resources can be used stably.
 Conserving natural environment
Conservation of the natural environment
JWA engages in environmental survey, revegetation, and vibration and noise pollution control to conserve the natural environment, including the local flora and fauna, ecosystems and landscapes. In addition, as a member of the local community, it engages in environmental conservation activities proactively.
Improvement of environment of downstream river
We are working on the improvement of river environment for the fish and other river creatures, providing a large amount of sand and gravel to the downstream rivers of the dams and flashing discharge within a short time to flash away the mud and mosses adhered to the gravel in the river and refresh them. As a result of such measures, in the case of Hitokura Dam of kawanishi City, Hyogo Pref., there were increasing number of small creatures on the bottom of the river such as may-fly, stone –fly, and caddis –fly, etc. and clean-water fish by about 5 times compared with the days before such river refreshment measures.
 Promoting international cooperation
Network of Asian River Basin Organizations (NARBO)
JWA strives for the social exchanges between the people of upstream and downstream areas to deepen the coordination with the water source areas where they show deep understanding and cooperation in organizing and managing the dam facilities and also with the water users downstream.See more