Princess, Poison & Trout (English)

Three Lakes

There are three lakes in Akita. One is Lake Towada on the border of Aomori Prefecture. Hachirogata is now landfilled. And Lake Tazawa. Legend says that the Buddhist monk Nansobo won to get Lake Towada from Hachiro Taroryu. Hachiro Taroryu lost to Nansobo and made Hachirogata near the sea, and later fell in love with Tatsuko in Lake Tazawa who also became a dragon. This is called the Legend of 3 lakes. And, the firewood thrown by mother of Tatsuko who saddened her daughter’s fate. The firewood became a trout.

Time flows much, and 1940, it’s a bad smell era of coming war. At this time, the national trout was caught up in the flow of the nation’s history and disappeared from Lake Tazawa. After 70 years, it suddenly appeared in 2010 at the West Lake of Mt. Fuji. There is a sad but precious story of modern country which makes that the country’s treasury trout disappears and reappears. It will be handed down.

Let’s start with the legendary story of Lake Tazawa.

Once upon a time, near Lake Tazawa, a daughter named Tatsuko lived with her mother. One day, the voice of god in the mountains is heard. It said, you, beauty, forever. After that, Tatsuko became beautiful day by day, and came to be called the princess of Lake Tazawa. Tatsuko wanted to keep her beauty forever, so she made a wish to a shrine by the lake. The shrine told her to drink the water of the spring on the day of the full moon. As the shrine said, Tatsuko secretly crossed the mountain, crossed the valley, and sought a spring. On the way, rain, wind and plants blocked the way.

When Tatsuko felt thirsty, she reached the spring. When she drank the water of the spring, but the thirst did not stop, then thunders are roaring around, a mountain tsunami occurred, and a big lake were built. Then the Tatsuko became a dragon. Tatsuko’s mother threw the burning firewood at the lake water. She roared that her daughter was not able to return to the human world.
  The legend said that this firewood became a trout and was called “Kunimasu” which means national trout. The Author boldly creates from the Japanese old story database “The Tale of Princess Tatsuko”, “The Tale of the Singing Sand” by Shigeo Miwa, and the legend of Tatsuko hanging on the lakeside, etc.


In the vicinity of Lake Tazawa, the hometown of Kunimasu, the huge amount of hot spring water come out. The amount is 8,400 liters per minute. This is the amount of water in the bathtub of 42 houses (200 liters per a house). This is one of the most acidic water sources in Japan. It is The Acidic Spring, Tamagawa Onsen. This hot spring water is PH1.3.  It is the strongest acidic water in Japan. When the wound is soaked, it hurts. This strongly acidic hot spring water is the blessing of nature that gives us trials and the fortune. And, it was a Kunimasu who disappeared in the flow of the age.

History of Tamagawa Poison Water (Acid Water)

Let’s take a look at the story on the Ministry of Land, Infrastructure, Transport and Tourism’s website [some of which I have made a modified () addition].

Big Spring, Tamagawa Onsen

The strongly acidic spring flowing out of the large spring of Tamagawa Onsen in the upper reaches of Tamagawa (which flows through the northern part of Akita Prefecture) turned the water of a river into acidic. Before the start of operation of the neutralization facility (by the former Ministry of Construction to be described later), pH at the Tamagawa Dam site is below pH4.0, which is a limit that does not affect civil engineering structures, Even at the downstream point of the Jindai Dam, which is the water intake point for agricultural water, the agricultural water standard pH6.0 to 7.5 was not secured.

(Omit several sentences)

1. The first measures taken were about 160 years ago (1841-1852), by the lord of the Akita Domain, Satake, and the head of the Kakunodate clan, Koemon Taguchi, his son, and his man Togoro Hiraka. They made efforts to exclude the strong acid water (at that time, to create a waterway to control the mixing of acidic spring water from the upstream and rainwater. It is said that they tried to reduce the acidity by mixing with sediment in the pond It is said that the work in the hot water of the strong acidity was done wearing the wooden box like boots. The effect of the construction, the yield increase per unit area, the labor cost reduction by ease of cultivation, and the corrosion avoidance of metals such as sickles and pots, were presented to acquire investment money. I was overwhelmed by the depth of the scientific and economic perspectives of the time).

Kouemon Taguchi

After the Meiji era, measures were attempted by Akita Prefecture and others, then some effects were made.

2. After the Meiji era, measures were attempted by Akita Prefecture and others, then some effects were made.
3. In 1939, the Tamagawa Water Control Plan was formulated for the purpose of electricity supply development and the promotion of agriculture, and a method was implemented to introduce and dilute Tamagawa water to Lake Tazawa.  [Tamagawa River Water Lake Tazawa Water Guide Started in 1910] (This was believed to acidify Lake Tazawa and lead to the death of many fish and shellfish, including Kunimasu.) Acid water countermeasures by this method were carried out continuously by Akita Prefecture and Tohoku Electric Power Co., Ltd., and although it initially had a certain effect, the water quality of Tamagawa has also decreased (again) due to acidification of Lake Tazawa, itself.
  For this reason, since 1972, Akita Prefecture, with the cooperation of Tohoku Electric Power Co., Ltd., has taken measures by simple limestone neutralization method.
4. However, this is not sufficient measures, and there was a strong demand for drastic measures from the local government and Akita Prefecture an et all. In response to this request, a review committee was held by five ministries (agriculture, trade, local-governance, environment, construction), and the Ministry of Construction, which was under construction at the time, as part of the Tamagawa Dam project, because of the large impact of acidic water on concrete dams, decided to work on measures against acidic water (the neutralization treatment facility was built by this).

Today, due to the hardships of various measures taken by our predecessors, water quality is gradually improving, and in Lake Tazawa, Ugui and other fish are also inhabiting (until here, slight modification and supplement by a writer).

In Lake Tazawa, the inhabitants of Ugui, which are resistant to acidic environments, have been confirmed, but others are only partially inhabited by released small fish. Ugui is highly environmentally adaptable and has become huge, reigning in the ecosystem of rivers with poor water quality. In fact, fishing for giant Ugui has become popular among some maniacs. Ugui is also a sad fish. As described in the Ministry of Land, Infrastructure, Transport and Tourism, the water quality of Lake Tazawa is gradually approaching neutrality, but it is a state of the surface layer. In the middle waters and the bottom of the lake, acidity is still high. It is also said that the bottom of the lake is beginning to accumulate lime used for neutralization.

The Tale of the Kingdom

Just before the acid water of Tamagawa was drawn to Lake Tazawa, eggs of Kunimasu were distributed to lakes throughout Japan in 1930 and 1935. In 1935, 100,000 eggs were sent to West Lake in Yamanashi Prefecture.

Akita Prefecture staked a prize on the search for surviving Kunimasu, in the 1990s. The prize money was raised from one million yen at first and five million yen at the end. Naturally, fishermen, fishing enthusiasts and bounty hunters across the country sent a fish to Akita government, but it was not verified.


In West Lake, a fish species called “Kuromas” has been captured, and it gained a reputation of good taste. It was in 2010 that this “chromas” was confirmed to be a Kunimasu. It is said that Kunimasu often sit still at the bottom of the lake rather than active fish. In a word, the Kunimasu is a weak fish. Kunimasu survived in the West Lake because the habitat areas of fish species such as the black bass of the carnivore are not overlapped. What a good luck!

From here, it is a story of the future for Kunimasu. There will be Tatsuko, Kouemon, and a dragon, the story is filled with water, mud, and it will be spun.

To return Kunimasu to Lake Tazawa that has been a home of the fish, the neutralization of Lake Tazawa is necessary, which still has a high acidity. However, there is a limit to neutralization using lime. There is another way to borrow the power of the microorganism to overcome acidity.

The papers published by Union Press, Science and Technology Research Vol. 7, No. 1, 2018, by Naoto Urano, Shintaro Nagaoka, and Kimihiko Okai of Tokyo University of Marine Science and Technology [ Yeasts with a strongly acidic environment]. Let’s take a look at the summary. I added some comments in () and omitted some of them. Though it is a little complicated, it is an important discussion. But you can skip to read to the bottom of the figure. The conclusion is that acidity can be neutralized by yeasts.

  The authors (of papers) have discovered a novel yeast (called “alkaline yeast”) that has the function of neutralizing the habitat and is derived from the strongly acidic hydrosphere. In this paper, we discuss the acid underwater mechanism, which is ecological, and environmentally friendly neutralization method by alkaline yeast. In Japan, strongly acidic freshwater spheres of pH 1-4, such as the upper reaches of the Azuma River in the Kusatsu region of Gunma Prefecture and the Tamagawa upstream in Senboku City, Akita Prefecture, are scattered, and the habitat of multicellular organisms (such as fish, clams and plants) are not usually observed in the water sphere. When the authors conducted a survey of single-celled organisms, prokaryotic (bacteria) were not detected, and eukaryotes (yeasts) formed the main microbiota. Isolated yeast is bacteria which are growable in acid environment of pH 1-3. Alkaline yeast was present in them. When culturing the alkaline yeast in an acidic medium, the cells release ammonium ion NH4+ by cutting the amino group of amino acids. It was found to neutralize the acidic solution. Next, it was searched for alkaline yeast in a general neutral freshwater sphere, 9. 4% was alkaline yeast. Yeast 28s rDNA D1/D2 domain sequence analysis (this is not explainable. In yeast and mold research, it seems to be determined that it is the same or different by doing such DNA analysis) in the alkaline yeast derived from the neutral hydrosphere, there were several strains(species) with the same sequence as the nucleotide sequence that the authors isolated from the strongly acidic hydrosphere and registered. These results, alkaline yeast is not distributed only in the strongly acidic hydrosphere. Alkaline yeast lives widely in the neutral hydrosphere, and also alkaline yeasts from both hydrosphere, exhibit the function of neutralizing water in an acidic environment. Furthermore, as an experiment, alkaline yeasts contained in the alginate gel beads (soft minimal tub such as gel) are filled in a column (like a tube). When acidic water (pH3. 6) was flown though the column, yeast continuously produced neutralized water (pH7 before and around). Then by passing through zeolite (a substance with small holes for adsorption which work for molecular sieve) filling in another column, NH4 + concentration in water was significantly reduced while maintaining the pH 7 vicinity. (In the later part of paper, the adsorption of aluminum, which weakens the action of alkaline yeast, is also described). Thus, it was possible to construct a bioreactor (device for performing biochemical reactions using a biocatalyst) that can produce environmentally friendly neutral water from strongly acidic water.

Mechanism of Bio Reactor

The authors believe that it is possible to use the neutralized water as part of the industrial water such as the living water of the resident, aquaculture and agriculture though it is not possible to produce a large amount of water by this method.

In this paper, experiments are conducted in a state (pH3.6) in which acidity is suppressed to some extent by lime, etc. Further, when performing neutralization by yeast on a large scale, it is also necessary to secure carbohydrate and amino acid (N) for food of yeast, it is likely to affect the water quality.

Another powerful test, using strongly acidic water has also been studied, which extract hydrogen. The source of Tamagawa Onsen can be used for generating hydrogen by reacting with aluminum. Through the generation of the hydrogen by this method, CO2 does not occur, it has attracted attention as superior to the current hydrogen generation method.

It is up to the microorganism to decide whether the microorganism returns the lake to natural water. We need to listen to their voice. It makes no sense of nature without hearing their voices. The legend of Lake Tazawa, the return of the Kunimasu, is accomplished for the first time when we regain the power to hear the voice of nature. In addition, if the extraction of energy from strong acids is added, there is a truly “a nostalgic future”.

The Future of Lake Environment

The pollution of the sea is already enormous. On the other hand, the environment of the lake where rainwater flows directly is still maintained. In lakes, leisure fishing and tourism have led to a deterioration on the natural environment. Originally, rich fishery resources should be captured in the moderate way and used as the blessings of nature. In addition to overfishing, there is a need to review the excessive fish farming.

Camping by the water is refreshing. The world is in a big camp boom. However, it is necessary to avoid throwing the exhaust gas in a clear environment, putting out a large amount of garbage, and putting a load on the environment. We must return to living with the blessings of nature.

Lake Tazawa, where fishermen can make a living by using natural fishing methods, will be the future of lake environment. There are countless microorganisms who support natural environment. We live with them; animals and plants also thrive with them. I hope it will be the waterside of the future.

In the past, footsteps on the beautiful lakeside made sand echoes across the surface of the lake. This is called “Musical Sand”. Now sand doesn’t play sound. The lime flowing in due to acid neutralization is adhere to the sand and lost the sound. The sandy beach of Lake Tazawa has long been called White Beach. There was no shallow water in this lake, and there was only one place, a shallow sandy beach, and it was “quartz sand”. It is said that the rock called “phenocryst” was decomposed by wind and rain for a long time, and it became fine particles and deposited on the lakeshore. White sand beach was spread to the edge of the lake water, and the “quartz sand” was laid, and the clearness of the lake water was further drawn. There was an old travel inn near the shore of White Beach, and the bathroom was on the garden. The poet, Yuki Aisoka, sang as follows.   

Tazawa, Hot water in Bathtub, White Sands are Sinking” (by Jihei Chiba, “The Story of the Mountain Lake” (1978)

An Old White Beach on a post card

Hidetoshi Shibata

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