The Ara River rises in the Chichibu Mountains of Saitama Prefecture, from where it flows southeast for some 140 km to reach the capital and discharge itself into Tokyo Bay. As its name (which means “rough”) implies, it used to be a violent river, swelling after heavy rains and raging across the wide flood plain of the Sumida, as the river is known in its lower reaches.
The big river was also an important natural defense for the shogun’s capital, and consequently throughout the Edo Period (1603-1867) few bridges were allowed to span it. Instead, ferryboats were used to make the crossing, operated under regulations enforced by the shogunate.
The 1830s woodcut illustrations by Hasegawa Settan show one of these ferries at Toda on the northwestern edge of the city. The boat, with a horse and several passengers aboard, is about to reach the shore, where more horses and passengers wait to be shuttled back. Meanwhile, another ferry is preparing to leave the other shore and, although the river looks quite high, all the horses we see appear quite at ease on what must have been a late afternoon, judging from the black silhouette of Mount Fuji and the surrounding ranges against the bright western sky.
About 7 km downstream from Toda, Iwabuchi was the crossing point for travelers on the Iwatsuki-kaido mentioned in this column last month. As at Toda, two ferryboats were in service there, and many of their passengers were probably pilgrims going to or from the popular Zenko-ji Temple in Kawaguchi, on what is now the Saitama Prefecture side of the river. As a result, the village of Iwabuchi thrived, catering to the constant stream of people waiting their turn to board a ferry.
Every now and then the shogun also passed through on an official journey to Nikko to pay homage to his ancestors buried there. Announcements of his travel plans invariably caused a commotion at usually peaceful Iwabuchi, because the villagers had to build a temporary bridge for him to use. This was made of scores of boats rounded up from all over the place, then lashed together to span the river’s 120-meter width and “paved” with wooden boards covered with earth.
Three days later, when the shogun returned and his long procession had walked back across, the bridge was disassembled, although toward the end of the shogunate it was allowed to remain in place permanently. However, no real, permanent bridge was built until 1928.
Iwabuchi is better known today for its Kyu Iwabuchi Suimon floodgate. Completed in 1924, the concrete sluice was instrumental in relieving eastern Tokyo from devastating floods. Though its role was taken over in 1982 by a new one built nearby, the old sluice continues to be the symbol of Iwabuchi.
For your visit, take the subway Namboku Line to Akabane Iwabuchi Station and leave by Exit 3. Make a sharp turn left into the town of Iwabuchi, with its cobweblike street layout much the same as in the Edo Period. Though visually nothing remains to convey its vibrant past, except a cluster of Buddhist temples and eroded stone statues poignantly standing in the narrow streets, when you reach Yakumo-jinja Shrine close to the riverside you might get a feeling of the town’s underlying community spirit.
In particular, in the right-hand corner of the shrine grounds, just before the second torii gate, this spirit is evident from a large stone there dedicated, as the inscription on it says, “To the Preservation of the Town Name of Iwabuchi.” Graced by a mossy stone lantern and low-growing goyo matsu (Pinus pentaphylla) on its sides, the stone commemorates the community’s eight-year battle with the government over their historic town’s name. In the nationwide address reform of the 1960s and ’70s, some other communities in Tokyo also refused to have their old district names wiped out, but Iwabuchi is the only one I know of that erected a monument to commemorate their victory.
Leaving the shrine, turn right and cross a footbridge over the Shinkashi, a tributary that soon joins the Sumida off to the right. By climbing the high embankment of the main stream ahead, you will get a delightful view of the Ara, with Kawaguchi on the other side and modern condominiums beside its green banks. Formerly an industrial city with a long history of iron-founding, another Settan print shows an old-fashioned factory there where pots and kettles are being made to supply Edo. Long gone now, though, Kawaguchi’s smoke-stack industry has been replaced by the altogether greener business of horticulture.
Long gone, too, are those boats lashed together, with the river-crossing now being achieved at a swishing speed by vehicles on the 600-meter-long Shin Arakawa Ohashi bridge and trains of the JR Takasaki and Tohoku railroads rattling over a green truss bridge.
However, turning right, your eyes will rest with pleasure on the old Iwabuchi sluice which divides the waters into two — the Sumida on the right and the much larger flow of the Arakawa Canal to the left. From here, too, the new sluice is visible in the distance, its blue color making a nice contrast with the red of its predecessor.
Before the old sluice and canal were built, all of the Ara’s waters used to go into the Sumida, resulting in frequent inundations of the city’s low-lying shitamachi districts. In the end, the national government undertook construction of the sluice following a devastating flood in 1910, whose repair bill soaked up 4.2 percent of Japan’s GDP.
After this massive enterprise was completed in 1924, it stood fast against the onslaught of frequent deluges, bearing testimony to the expertise of its chief architect, Akira Aoyama. When he was assigned to the project in 1915, Aoyama had just returned from a seven-year spell working as the sole Japanese involved in the construction of the Panama Canal, then the most ambitious waterway engineering anywhere in the world. Applying his hard-won knowledge and skills, he successfully masterminded Japan’s first large-scale construction using steel-reinforced concrete.
To this day, it’s still possible to walk across the nearly 80-year-old sluice, enjoying the breeze over the water. For your return, backtrack to the subway station or, if the traffic doesn’t bother you, you might like to walk onto the big bridge to get a different view of the river from there. If you are hungry, the Hosokawa eatery (open 12-9 p.m.; closed Mondays) opposite the subway’s Exit 3 — across the intersection — serves reasonably priced, home-cooking-style lunches favored by local workers.