Magic wand to make stinky water clean: Japanese first modern waterworks

Before visiting the largest “Citizen” Forest of Yokohama, let’s talk again about 4 large water reservoirs for Kanagawa Prefecture. The line-up is

Name of the Dam	Accompanying Lake	Operational since	Water Storage Volume (million m3)	Catchment Area (km2)
Sagami Dam	Lake Sagami	1947	48.2	1200
Shiroyama Dam	Lake Tsukui	1965	51.2
Miho Dam	Lake Tanzawa	1979	54.5	159
Miyagase Dam	Lake Miyagase	2002	183	100

These dams (plus one more that I tell you next week) provide 90% of tap water in Kanagawa. The remaining 10% is for Hadano City 秦野市 and the surrounding area who uses underground water system of Mizunashi River 水無川 from Tanzawa. Unlike Tokyo, Kanagawa Prefecture procures all the water within its border. Water source forests in western Kanagawa receive lots of rain so that Kanagawa seldom has water shortage. Moreover, Kanagawa Water Source Authority神奈川県内広域水道企業団 and Waterworks Bureaus of cities have an impressive network to smooth out water supply for the entire prefecture. The dams except Miyagase have the western Tanzawa 丹沢山系 and Okutama 奥多摩山系 mountains as the catchment area where it rains a lot. Miyagase Dam 宮ケ瀬ダム asks the eastern Tanzawa only as its catchment area, but its capacity is the largest. The water offices connect Sagami 相模ダム and Shiroyama 城山ダム dams with Miyagase Dam by 2 large underground aqueducts to store water. In addition to this, the underground aqueducts also connect Iizumi 飯泉取水堰, Sagami 相模大堰 and Samukawa 寒川取水堰 waterintake facilities. Iizumi facility collects water from Sakawa River 酒匂川 stored at Miho Dam 三保ダム. Sagami and Samukawa facilities withdraw H2O from Sagami River 相模川 stored in Sagami, Tsukui, and Miyagase Dams. The connection among water facilities stabilizes water supply from these 2 rivers and distribute it to the population centers of the prefecture, including Yokohama. 

Lake Sagami created by Sagami Dam

Lake Tsukui created by Shiroyama Dam

Lake Tanzawa created by Miho Dam

Lake Miyagase, created by Miyagase Dam

Samukawa water intake facility on Sagami River

A prefecture where 1/3 of it is in the megalopolis Tokyo area, i.e. Yokohama, Kawasaki, Fujisawa, and Sagamihara, rarity of drought is an achievement. I understand the pride of officers for the prefectural government or the city halls in Kanagawa when they describe the arrangement from their wise water policy making and execution with a long-term view. Er, well, BUT, these days I felt the very beginning of the foresight would be thanks to the coincidence of the history. The lucky chance happened some 150 years ago from the now-largest “citizen” forest of Yokohama. And that was because Japan closed itself to the outer world between 1639 and 1854. In those days, I don’t think there was anybody who cleverly expected the 21st century waterworks system of Kanagawa. Taking a credit of drought-less Kanagawa should require some modesty. Now I explain you why I think so.

When Commodore Matthew Perry of the US prised open the Japanese door for westerners in 1854, Edo (Tokyo) government 徳川幕府 did not want to be physically near to the white-faced people at all. They first let the foreigners have their consulate in Shimoda of Izu Peninsula 伊豆下田, some 110K south from Tokyo, and Hakodate in Hokkaido 函館, about 800K north from Tokyo. Soon Imperialists’ gun diplomacy forced the Shogun to tolerate them nearer. In 1858, the Port of Yokohama, 20K south from the Edo Castle (now, the　Imperial Palace), was opened. Even though, until 1899 Japan did not allow non-nationals to move around in the country. The concentration camp of foreigners in Yokohama was enforced for about 40 years. The port Europeans (; then, Americans became busy with their Civil War) had to stay that long was not so comfortable at the beginning. Before 1858, this part of the beach of Edo (Tokyo) Bay was salty swamps with occasional sandbanks for a small impoverished village of fishermen’s huts, called Yokohama Village. Inevitably for sandy places surrounded by salty swamps, the water quality was extremely poor. Before 1858, the area was frequently hit by the outbreaks of cholera. Do you remember in August 2015 we visited Yasaka Shrine 戸塚八坂神社 near Masakarigafuchi Citizen Forest まさかりが淵市民の森? The Shintoism Shrine is famous for the transgender festival every 14^th of July. The carnival is said to be started in the 17^th century to “pacify” demon of cholera. The shrine is about 8K inland from the newly established port.

Yasaka Shrine against cholera epidemic

In 1868, Edo Shogunate was replaced by Meiji Government 明治政府 who was eager to industrialize and imperialize Japan. Meanwhile, the new international port attracted lots of people from all over Japan who needed water too. The population of Yokohama exploded. In 1868, Yokohama already had 28589 residents including 1070 foreigners. By 1876, the population became 56048. For a while, the government let Yokohama to follow Tokyo about water. Some 300 years earlier, the place around Edo Castle 江戸城 was also a swamp. For centuries the Shogunate government reclaimed land, and built waterworks in ditch such as Tamagawa Josui Waterworks 玉川上水. In 1871, the mandarins for Yokohama made private entrepreneurs build ditches and carry water in wooden pipe from Tama River 多摩川, just like for Edo. According to Prof. Keiko Izumiof Iwate Prefectural University, the volume of H2O reaching to the new port in this way could not keep pace with the increasing number of residents. Worse, open-air ditches with hastily connected wooden pipes contaminated the contents at once. Outbreaks of cholera, again and again. In addition, rashly constructed new town was prone to large fire, and lack of water created the serious fire incidents. Water sellers with wooden buckets for exorbitant price did thriving business in Yokohama. On the other hand, luckily for westerners they had superior weaponry to Japan. They went like “OK, we stay at the place you designated for us. But, hey, you have to make our place nicer for our life in Japan. Otherwise, we’re gonna push you trade treaties that would extract silver, silk, and any Japanese goodies as much as possible while we are completely immune to Japanese law. By the way, our gun can kill Yokohama people easily whenever we want to.” The new government hated the international trade treaties concluded during the Shogunate. They had to provide good deals to invite westerners to the renegotiation table. i.e., Japan needed better infrastructure for Yokohama ghetto of foreigners. They realized private water business in old Edo style did not work.

A remnant of old wooden pipe
used for the private water business in Yokohama.

A water seller in early days of the port of Yokohama.
We can find these historical artifacts in
Yokohama Waterworks Commemoration Hall 横浜水道記念館.
It’s a fun museum with lots of exhibits
about mechanics of waterworks in Yokohama,
old and new.

So, in 1883, the Meiji government invited British Army Engineer Brigade Colonel H. S. Palmer to create project information documents to build a modern waterworks system for Yokohama. In his proposal, Palmer presented 2 water sources for Yokohama; Tama River and Sagami River. Kanagawa Prefectural government chose Sagami River since all the suggested water intake facilities from Sagami River was in Kanagawa Prefecture. (Ah-ha, so Kanagawa is historically stingy about water towards Tokyo!) The construction started in 1885 and the system for Yokohama became operational in 1887. It was the first modern waterworks in Japan, earlier than for Tokyo. For more than 150 years, the system continue withdrawing water from near Tsukui Lake, or, to be more exact, from a tributary of Sagami River called Doshi River 道志川. It sends water to Yokohama only by the gravitational pull created by the difference of elevation between the water source and Yokohama’s water purification plants some 53km apart; no pumping is used at all. From the beginning the network goes through the closed and sometimes underground pipes, which made it possible to convey the water to the destinations “as-is” at the intake facility. As Prof. Izumi pointed out, the design made the water quality at the source all the more important. All sound very difficult for a mega national project of the late 19^th century. Why, then, could the endeavor be completed in only 4 years from the inception? Well, it’s because of the water source forest surrounding the water intake facility in Palmer’s design. It’s Doshi Village Water Source Forest 道志村水源林, owned by the city of Yokohama, but situated in Yamanashi Prefecture. That’s my topic next week. It’s a story possibly similar to the international relation along Mekong River, or for Rogun Dam of Tajikistan.

Doshi River along the Aoyama Settling Basin 青山沈でん池

Kanagawa Water Source Authority 神奈川県内広域水道企業団

1194 Yasashi-cho, Asahi-ku, Yokohama, 241-8525

Phone: 045-363-1111

Yokohama Waterworks Bureau 横浜市水道局

Phone: 045-847-6262

FAX: 045-848-4281

http://www.city.yokohama.lg.jp/suidou/