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Hamura Weir (羽村堰)

This entry is in the series Along the Tama
If you happen to be near Hamura or ever cycle the Tama upstream, take a short stop at the Hamura Weir (羽村堰 Hamura zeki), an interesting place in the local history of Edo, modern-day Tōkyō.

Hamura Weir (羽村堰)

The weir marks the historic spot where the Tamagawa Aqueduct (玉川上水 Tamagawa Jōsui) starts. The 42-kilometre long aqueduct was constructed in the Edo period to divert drinking and fire fighting water from the Tama River to Edo and provide irrigation to farming villages. The first attempt to create an aqueduct further downstream failed when the water channelled at the Hino intake seeped away due to the high permeability of the soil, a phenomenon called mizukuraido (水喰土). The second attempt close to Fussa hit bedrock and proved more successful.

Hamura Weir (羽村堰)

Construction work started in 1653 and was completed in only 18 months. Two brothers supervised the project: Seiemon (清右衛門, d.1696) and his older brother Shōeimon (庄右衛門, 1622-1695), most likely peasants living close to the river. They were later allowed to adopt the surname "Tamagawa" (玉川) as a reward for their achievements. The Tamagawa clan remained in charge of Edo's water supply until 1739. The two brothers are buried at Shōtoku-ji temple (聖徳寺) in Tōkyō's Taitō Ward.

Hamura Weir (羽村堰)

The bronze statue of the Tamagawa brothers (玉川兄弟) was erected in 1958.

The Tamagawa Aqueduct was also used as a stream channel for log rafts (筏 ikada). Trees felled further upstream in the Ōme area (青梅下げ Ōmezai) were floated down the Tama and had to pass the Hamura Weir. This posed a serious challenge to the raftsmen, as the timber often caused extensive damage to the weir. In 1718, the shogunate imposed a complete ban on log rafts.

The raftsmen who lived in the 42 villages administered by the Mita clan west of Hamura pleaded to the shogunal authorities to reopen the passage. In 1721, a new stream channel was built, and the floating of log rafts (堰落し seki otoshi) continued on a strict schedule until the end of the Taishō Period.

Hamura Weir (羽村堰)

Ushiwaku 牛枠 (川倉水制)

Kawagura (川倉) are traditional methods of preventing floods and dyke breaches by controlling the velocity of river currents. The most common type of kawagura are ushiwaku (牛枠, "cow frames", as their shape resembles that of cows). The wooden frame is placed in the river and fixed in place with a basket filled with boulders from the riverbed to resist the force of the water. This was a brilliant way to strengthen the embankments and at the same time control floods.

Hamura Weir (羽村堰)

Hamura Weir (羽村堰)

Hamura Weir (羽村堰)


  • Hane, Hamura, Tokyo 205-0012
  • Closest station: JR Hamura Station (Ōme Line), a 20-minute walk to Hamura Weir.
Next entry in the series 'Along the Tama': More Tamagawa Vistas
  • Informative
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Here's another photo of the Tamagawa brothers: one of them is holding a measuring rod, the other one a measuring rope.


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羽村堰 〒205-0012 東京都羽村市羽

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