(R15) Yazawa-gawa river 谷沢川 (やざわがわ）

The Yazawa-gawa river 谷沢川 (やざわがわ） is famous but few people know its name. The river is responsible for carving-out the lovely Todoroki Keikoku valley 等々力渓谷, a spot named to my – and many other – best-of-Tokyo lists. But the name of the river is not well-remembered. Unlike many rivers in Tokyo, this one is sparingly labelled; even the river’s signs are faded and difficult to read (map):

The upper half of the river, originating from a spring near Yoga Station 用賀駅, is unremarkable, having been straightened prior to 1945. One item of note is an odd little park: 中町一丁目広場. This secluded bulge of land, reachable only by a pedestrian bridge, is bound by the Yazawagawa and the Tokyu-Oimachi train line (map).

Then there’s the Todoroki Keikoku, a lush, steep ravine cutting through a residential neighborhood. (See: Todoroki Ravine Park map 等々力渓谷公園の地図)

Downstream of the Todoroki Valley is the curious crossing of the Yazawa-gawa and the Marukogawa (map). Because the Marukogawa was part of the Rokugo yosui 六郷用水 canal system, a pipe was used to segregate the waters of the Marukogawa from the waters of the Yazawa-gawa; I don’t recall where I read this, but it bears logical scrutiny and appears consistent with the way the rivers interact today, as seen in the following map: