Rivers in Japan are classified according to criteria set by the , which was introduced in 1967. Rivers are designated as Class A or Class B river systems by the

Ministry of Land, Infrastructure, Transport and Tourism The , abbreviated MLIT, is a ministry of the Japanese government.国土交通省設置法 ...

(MLIT).

Class A rivers

is a designation applied to rivers and waterways deemed to be important to the economy of the nation as a whole, as well as those deemed important to the conservation of nature within Japan. There are currently 109 rivers with this designation.

List of Class A river systems

The number of

dams A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

only includes existing and unestablished dams that meet the criteria ( or more in bank height) of the River Law. The management entity is irrelevant. The number in parentheses is the number of dams on the main river, excluding

tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainag ...

. The number of dams does not always exceed the number of hydroelectric plants because plants with intake

weirs A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of l ...

less than high are not considered dams. The acronym ''BOD'' refers to

biochemical oxygen demand Biochemical oxygen demand (BOD) is the amount of dissolved oxygen (DO) needed (i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at a certain temperature over a specific time period. ...

Hokkaidō Development Bureau

Tōhoku Development Bureau

Kantō Development Bureau

Hokuriku Development Bureau

Chūbu Development Bureau

Kinki Development Bureau

Chūgoku Development Bureau

Shikoku Development Bureau

Kyūshū Development Bureau

Class B rivers

The smaller, but important rivers are designated as , nominated and managed by the local governments at the prefecture level, but reported to and concurred by the central government.

References

{{japan-law-stub Environmental law in Japan /