Houkigawa

A tributary of the Naka River that flows through the northern part of Tochigi Prefecture, Nasushiobara City, Yaita City, Otawara City, and Nakagawa Town in Nasu County. Its drainage area is 527.5 square kilometers, and its river length is 55 kilometers. It originates in the mountains south of Ogashira Pass, merges with Utosawa and Akagawa, and enters the Shiobara Basin, passing through Furumachi, Monzen, Hataori, and other areas in Shiobara Onsen, and merges with the Kanomata River, which originates in Takaharayama and flows north, at Shiogama. It flows through deep gorges such as Fukuwatari and Oami, and enters the Nasu Basin from Sekiya. It washes over the northern edge of the Enna Hills (also known as the Kitsuregawa Hills), merges with the Sabi River in the southeastern part of the basin, and then joins the Naka River. The beauty of the valley near Oami is worthy of the name of Nikko National Park. You can fish for yamame trout, iwana, and iso (dace) in the upper reaches, and sweetfish in the middle and lower reaches. The dam is used for irrigating rice fields in the basin and also generates hydroelectric power. The prefectural Shiobara Dam in Yunohara was completed in 1979 (Showa 54) as a multipurpose dam for flood control, irrigation, etc.

[Mitsue Hirayama]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

栃木県北部、那須塩原(なすしおばら)市、矢板(やいた)市、大田原市、那須郡那珂川(なかがわ)町を流れる那珂川の支流。流域面積527.5平方キロメートル、流路長55キロメートル。尾頭(おがしら)峠南の山中に源を発し、善知鳥沢(うとうさわ)、赤川などをあわせて塩原盆地に入り、塩原温泉の古町(ふるまち)、門前、畑下(はたおり)などを経て塩釜(しおがま)で高原(たかはら)山に発して北流する鹿股(かのまた)川をあわせ、福渡(ふくわた)、大網(おおあみ)など深い峡谷を流れて関谷から那須(なす)盆地に出、塩那(えんな)丘陵（別名喜連川(きつれがわ)丘陵）の北縁を洗い、同盆地の南東部で蛇尾(さび)川をあわせてから那珂川に合流する。大網付近の渓谷美は日光国立公園の名に恥じない。上流ではヤマメ、イワナ、アイソ（ウグイ）、中・下流ではアユが釣れる。流域の水田灌漑(かんがい)に利用されるほか、水力発電も行われる。夕の原にある県営塩原ダムは、洪水調節・灌漑などの多目的ダムとして1979年（昭和54）に完成した。

［平山光衛］

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