Destructive effects of the Estuary Dam on the Nagara River's environment, and the program for its regeneration.

Shiro Kasuya

Department of Environmental Science,

Faculty of Regional Study, Gifu University

Abstract

The plan of the Nagara River estuary dam was issued in 1960. The purpose was a supply of the fresh water to Ise Bay industrial area. Though it was the plan for supporting the economic growth, a water demand drastically did not expand afterwards, and the opposition movement mainly on the fishery party was also intensified. After the "Anpachi flood damage" in1976, however, the flood control purpose of the dam was emphasized. The river bottom must be dredged in order to run the flood safely. The salt water will go up, when it will be so done, and the agriculture salt damage will be caused. Estuary dam, which stops this, calls it the necessity. The opposition movement once ceases, and it began construction in 1988. It was almost simultaneous, and the new opposition movement mainly on environmental problem became popular. However, the operation was started in 1995, while the fear of the adverse effect to the environment does not fade away.

Afterwards, the sludge piles up in the riverbed, benthoses such as the clams disappear almost, and algae breed in large quantities. Sharp decreases in the area of reed, and in catch of sweetfish and rhododendron lateritium trout are being clarified. Whether such large facilities and high control cost are necessary for only the inhibiting of upstream movement of brine, and whether the destruction of the environment permitted for only such a purpose, should be considered.

Firstly it is necessary to recover the destroyed environment. Furthermore, we need a new management of the catchment area that extends to the sea from the mountain, in which people don't depend only on dam and embankment. Excluding the myth without the dyke break, it should change in the countermeasure to the flooding and dyke break.

1.　National and regional background.

1-1. Historical background.

Postwar Japan passed the Comprehensive National Land Development Law (1950) and the Comprehensive National Development Plan (1962) in order to speed up the process of recovery. This was followed, in 1977, by the 3rd National Comprehensive Development Plan, and then in 1987 by the 4th National Comprehensive Development Plan. Through these plans Japan accomplished the so-called 'advanced economic growth' which has attracted worldwide attention. Against this background one issue became more and more significant: the maintenance of an industrial water supply for the Ise Bay Coast area. At the same time, however, society's attention was being drawn to the phenomenon of 'Yokkaichi Asthma', caused by the pollution of the air in the area due to the depletion of nature and the destruction of the environment. From 1965, certain problems, namely, the pollution of air and water, started to be considered in work such as the Industrial Pollution Preliminary Survey.

1-2. Project History.

The Nagara River Estuary Dam project was conceived in 1960, then decided to build in a cabinet meeting at 1968. Despite many opposition movements, construction began in 1988, and the dam started operating in July of 1995 after 35 years of expense. The purpose of the estuary dam was originally that of irrigation. It was intended that the dam would supply fresh water to the Ise Bay Combine (Power Station), which was also planned during the advanced economic growth era. This growth slowed finally as a result of the oil crises, and the demand for water began to drop significantly. Despite this, the government drafted excessively large forecasts for water demand. In the Kiso River Water System Resources Development Master Plan (the full plan), the prediction was made that in 1985 the additional water demand would be 108t/sec, as opposed to 70t/sec in 1973. This prediction was criticized as having no basis in reality, and being merely a bureaucratic exercise. In actual fact, results from 1985 to 1995 showed only a slight change, up to, but staying less than 80 t/sec. The next plan in 1993, which was released inevitably, reflected a decrease in the predicted water demand, showing a predicted additional demand of only 44t/sec for the year 2000. The additional 22.5t/sec which had been planned as the contents of the estuary dam had been proven to be totally unnecessary in the face of a water demand which was almost at a standstill (Fig. 1, Togashi, K). In fact, not only the Nagara River Estuary Dam but also the Tokuyama Dam in Ibi River, which was already under construction, was now unnecessary. There is currently no possibility that either social or economic conditions will change sufficiently to require an increased water supply in the near future.

1-3. Nagara River Basin.

1-3-1. Overview and the History of the Nagara River. The Nagara River, along with the Kushiro River, is known as one of the last 'limpid rivers', and had no dam at any point. The Nagara River has its source on the mountain Dainichidake (altitude 1709m), in Takasu Village in the Gujo District of Central Honshu. It is a Class A river, with a main watercourse which extends 166km, and a drainage area which extends to around 2000 square kilometers. It flows into the Pacific Ocean at the Ise Bay (Fig. 2 and 3). The upper part of the river flows from the source to Hachiman Town (altitude 210m), approximately 30km. From Hachiman Town to Mino City (altitude approximately 80m) the river runs through a valley for around 35km, although corrosion to the banks, due to the recurring strata of hard chart layers and soft shale layers, and a sandstone bed, in an area of narrow width, has meant that a row of plains now stretch along this area. As the river enters Mino City, it joins with the biggest of its tributaries, the Itadori River, to form the Chuno Basin. North East of Seki City, the southerly flow bends westwards, and heads into Gifu City, deep in the Nohbi Plain. It reverts to a southerly direction at Hozumi Town in Motosu District, and heads for Ise Bay. In this stretch it joins with the Ijira, Arata and Sakai Rivers, and wastewater from Gifu City and the surrounding areas is added when these rivers join.

There is no deep valley at any point, and due to geomorphologic factors such as the continued existence of homes and farms in the area, any plans for dams on the river had been rejected for many years. As a result, the natural environment was preserved to an extent, which is unusual in rivers, which flow through urban areas. Even today, Gifu City boasts a rarity: a river bathing area in the very center of the town. Fish of many sorts are plentiful; there have been 126 species, including sea fishes living in river mouth, recorded in the river so far, which beats the 120 species recorded at the Shimanto River (Fig. 2). In tests carried out under identical conditions by the Environment Agency in 1985, Nagara River came 3rd, with 62 species, beaten only by Shinano River and the Chikugo River, both of which recorded 63 species. Plant life in the area is also plentiful, with 168 species in 44 classes being recorded, including the Monochoria korsakowii and Penthorum chinese, both of which are mentioned in the Red Data Book as 'endangered species'. In the lower regions of the river, there are marshes and reed fields, which support many sorts of bird life. There have been 133 species of bird recorded at present. There are additionally 11 species (from 8 families) of mammal living in the area. 1-3-2 The cities, towns and villages of the river basin, and the population. The Nagara River belongs to Gifu Prefecture in most of the basin, and the estuary flows in respect of Mie Prefecture. The very much small part in the river contacts Aichi Prefecture. To the basin, 4 cities, 10 towns, 4 villages extend, and the total population is 736,681 persons (data on December the first, 1999).

1-3-3 Tourism and recreation in the River area (Fig. 4)

There are more than 16 ski resorts in the mountains surrounding the Nagara River. There are also over 20 golf clubs. Along the river itself, there is river stream fishing of dwarf rill trout and other fish, as well as various forms of tourism involving the sweetfish, such as sweetfish fishing, weir fishing and cormorant fishing. There are also 3 Prefecturally Designated Parks, in Oku Nagara, Senbonmatsubara, and Seseragi Valley. There are over 12 hot spring resorts, more than 19 valleys and waterfalls, more than 22 lakes, limestone caves, mountains and plateaus, making the area extremely famous and well-visited. There are 17 castles or ruins of castles, including Gifu Castle and Kano Castle, as well as more than 93 temples and shrines. Many historical artifacts remain in the area, such as the Kotozuka ancient tomb, Oda Nobunaga's house, and the Houreki era's water works.

2. Plans for the Dam.

2-1. The main contents and purpose of the plans for the Nagara River Estuary Dam.

Contents 1. Provision of fresh water.

The ensuring of a new supply of 22.5t/sec of fresh water was the main purpose of the dam (Table 1). Aichi Prefecture and Nagoya City, who had rights to the water, gave their consent early on, but Mie Prefecture opposed the plan for financial reasons. In the end, Aichi Prefecture and Nagara City agreed to undertake part of the financial burden of using the water, and in 1987 Mie Prefecture gave their consent.

Contents 2. Flood prevention.

After visiting the area, which suffered the 'Anpachi Flood Damage' in 1976 (note 1), where intensive rain had caused the banks of the main river to collapse, the plans for the estuary dam changed to include the purpose of controlling water levels. There is a need to dredge and extend the river channel in order to release flood water safely, but when the Mound (the area approximately 15km from the estuary where the river bed is raised) is dredged, agricultural damage can occur due to seawater rising up the river channel. There is a theory, therefore, which states that the estuary dam is necessary in order to achieve flood control. In 1978, the governor of Gifu Prefecture, where most of the flood damage occurred, gave consent to the building of the dam for these reasons.　

The dyke break was done in the step of the fireman who patrolled the embankment. The 2 persons died and the about 60,000 door received the inundation damage.

Contents 3. Compensation for the fishing industry.

At the beginning, almost all the fishermen in the area opposed the project. In 1973, a group of 26,000 plaintiffs, with the fishing co-operatives at its center, began legal action to have the building of the estuary dam abandoned. Later, the problem of compensation was settled, and in 1978 that action was dropped, and the 3 co-operatives that maintained their stand right until the end, including the Akasuka co-operative, dropped their opposition in 1988. Once these agreements had been given, the work was able to begin in 1989, at a gross building cost of 150 billion yen.

2-2 Benefits of the Estuary Dam.

2-2-1. Present water use and profit from the use of the newly provided water.

Before the dam was built, North Ise's industrial water supply (allocation of 2.95t/sec), Fukuhara irrigation supply (allocation of 0.256t/sec for agriculture), Nagashima Town's water supply, irrigation supply and channel maintenance supply (allocation 1.22t/sec), as well as Hashima City, Kaizu Town and Hirata Town's irrigation water supply (combined allocation of 8.78t/sec) were all taken from the Nagara River (Fig. 5). The Construction Ministry asserts that since the dam has stopped seawater from rising up the river, it has stabilized the water supply for these areas. No new demand for industrial water supply has been recorded. As a result, the water supply has been diverted into tap water, causing the problems that are recorded further on in this document.

2-2-2. Benefits of flood control.

The volume of dredging carried out by the Construction Ministry was as follows: 6 million cubic meters between the estuary and the 3km site, 6 million cubic meters between the 3km site and the 7km site, and 13 million cubic meters between the 7km site and the 30km site. As a result of this work, between 25 and 30 km upstream from the estuary the water level was lowered by 1.43m, enabling flood waters of 7,500 cubic meters / sec to flow safely.

2-2-3. Tourism and recreation.

The flooded area, which extends over 30km, is utilized as a marina and triathlon course. Occasionally bass fishermen or carp / crucian carp fishermen have also been sighted in the area.

2-2-4. Embankment reinforcement and assistance to local community organizations.

3. Anticipated negative effects.

3-1. The threat of environmental deterioration.

In 1990, the NGO known as the Nagara River Downstream Area Biological Survey Group (headed by Professor K. Yamauchi of Gifu University, and known henceforth as the Survey Group) was formed to investigate effects on the ecosystem, and began to survey the distribution of organisms in the Nagara River before the dam went into operation. The Survey Group feared negative effects on the biota, and issued questions on 49 subjects to the Construction Ministry to this effect. In response, the Construction Ministry's Water Resources Development Corporation issued the 'Response to the Questions regarding the Nagara River Estuary Dam' (hereafter the 'Response'). In this Response, the Ministry stated that the effect to the biota of the dam's operation would be extremely small, or even non-existent, and in response to some of the areas raised as concerns they promised artificial countermeasures to reduce the effect to zero.

3-2 The Construction Ministry's predictions of environmental impact.

3-2-1 Low oxygen levels in the riverbed upstream of the dam during the summer season.

The Construction Ministry began main operations of the dam without having test data for the summer season. In place of this, it published data from similar dam areas throughout the country, and asserted that 'inferring from formation conditions of thermoclines in similar water areas, there is no clear threat of thermoclines being formed in even extreme drought conditions like those experienced in the summer of 1994, and there is no fear of the dissolved oxygen (DO) level dropping to extreme low levels'. This was the 'conclusion' published in the Nagara River Estuary Dam Research Report, volume 2, 4-625, lines 5-8. The Report contained a huge volume - 123 pages - of material in order to give this conclusion (p. 145 to 267).

3-2-2. Water bloom and outbreak of algae.

'As the area upstream of the weir always has a plentiful supply of water flowing through it, it is unthinkable that water bloom or any other sort of deterioration of water conditions should occur.' ('More Nagara River 4').

'In similar dams already in operation, there is no precedent for the outbreak of algae to the extent that it has caused the phenomenon known as water bloom in any case where the water velocity is over 1cm/sec. As such, there is judged to be almost no possibility that there could be an algae outbreak to the extent of causing water bloom in the Nagara River Estuary Dam area.' ('the Response').
3-2-3. Brackish water area.

'The brackish water area in the Nagara River extends for approximately 15km. Once the dam is completed, the water upstream of the dam will become freshwater, and the brackish water area will be that below the dam only. This will reduce the brackish water area to only 5.4km, but it will not remove it completely.' ('the Response').

'Professor Kasuya has been making remarks which suit his own cause, and which are nothing more than points, and the idea that this is going to become the estuary of death has nothing to do with scientific reason, but is simply a product of his imagination…' (Rivers Section Chief Takemura, minutes of the first new dialogue meeting, p.45)

3-2-4 Brackish water clams (Corbicula japonica)

'From the dam to the estuary mouth, the salinity of the river bed will show no change, and as such there should be no change in the brackish water clam population.' 'The construction and dredging will have some effect on the brackish water clam.' ('the Response')

3-2-5 Sweetfish (Plecoglossus altivelis altivelis) and rhododendron lateritium trout (Oncorhynchus masou ishikawae).

It was confirmed that new fishway have been effective for sweetfish and rhododendron lateritium trout. Given that there are a large number of larval fishes being released into the river, it was judged that there would be little effect on their populations. 3-2-6. The Palaemon (Macrobrachium latydactylus)

'In the case of the Kiso River Dam, the Tone Estuary Dam, and the Chikugo Estuary Dam, where spawning activities were monitored, the Palaemon was confirmed as using the fish routes and migrating up river. This led to the conclusion that there should be no significant effect on the life cycle of the Palaemon from the Estuary Dam.' ('the Response').

3-2-6. The Eriocheir (Eriocheir japonicus)

This will move on to deep water in the brackish areas downstream of the dam, and in the sea, once the dam is completed.

3-2-7. The eel (Anguilla japonica).

'Enough "shirasu" eel (larvae of Anguilla japonica) will be able to ascend the Nagara River to ensure continued production in the area. "Shirasu" eels can climb the fishway easily with a 0.4m/sec water velocity, or a 1.5m/sec water velocity once they reach 15 _ 30 cm in length.'

3-2-8. Cottidae and Gobies

Regarding Cottus pollux, it is judged that there will be minimal effect on its life cycle overall, with countermeasures being put into place to combat any small decrease in population. Gobies have a strength advantage in ascending the river over Cottidae, because of their suckers, and as such the effect on their life cycle is judged to be minimal.

3-2-9. Short-necked clams and hard clams.

The effects of the construction on the short-necked and hard-necked clams, which inhabit the sea areas and the estuary area, are judged to be minimal.

3-2-10. Sesarma (Sesarmops intermedium).

Can move to upstream of the dam by walking.

3-2-11. Reeds (phragmites australis).

Since areas upstream of the dam will lose tidal influence, some effect can be expected on the reed growth in the area, and replanting of the vegetation will be carried out. In connection with the dam construction, the reed fields, which were approximately 300 ha in area, will be reduced to approximately 100 ha.

3-2-12. Chironomid.

'It is judged that there will not be significant enough change in the water quality or river bed conditions after the completion of the dam construction, to become the cause of a large volume outbreak of chironomid.' ('the Response').

3-3.　Proven negative effects on the environment.

3-3-1. Effects proven by test flooding.

In analyzing the data gathered by the Construction Ministry from a test flooding carried out in October 1994, it is clearly shown that downstream of the dam, when the gates are closed, halocline is formed (Fig. 6), oxygen levels on the river bed become extremely low, and there is a counter-flow generated. Additionally, in a test designed to examine the viability of brackish water clams, clams were placed in wire boxes on the riverbed, and contrary to expectations, the clams in the seawater below the dam, rather than those in the fresh water above it, were almost completely wiped out. These results caused NGO member to issue the warning, along with the figures issued in the chart (Fig. 7), at the "round table discussion" (note 2) which preceded the start of operations of the dam, that the project was creating profound influences. The operation of the dam, however, was approved.

=note 2=

Exhibition panel discussion with NGO member and people of learning and experience and the Ministry of Construction was carried out before operations of the dam.

3-3-2. Observed negative effects on the environment.

3-3-2-1. The destruction of the brackish water area.

In the brackish water area salt and fresh water mix periodically (with tides, and at the spring and neap tide), and dynamically (the vertical and horizontal salinity gradients). This leads to the creation of many and various environments, and the number of species, and quantity of organisms per area living there is high, even on an international scale. The dam would unify these environments dramatically. Seawater would be completely stopped from flowing upstream, and the periodic and dynamic mixing of seawater with the fresh would cease. The fresh water, which builds up behind the dam, would be released into the seawater below the dam. As the fresh water is lighter, and does not have a proper chance to mix, there is an upper fresh water and a lower seawater layer formed, with a distinct boundary between the two. Subsequent to the start of operation of the dam, the Survey Group carried out an ultrasound survey, and from the reflection of the ultrasound waves, found that there is a clear formation of layers. It was shown that there are actually 3 layers at some times (Fig 8). It is extremely difficult for oxygen from the air to cross these layers and reach the riverbed. Even when DO levels in the surface and lower layers of the flooded area above the dam were almost identical, when the barriers were closed, the surface level in the area below the dam was 7.2, 7.1, and 6.2 mg/l, while the levels in the lower layer were 2.3, 1.9, and 1.4 mg/l respectively (Fig. 9). This showed the extreme low to which DO levels had fallen. This was a death blow to brackish water clams and other organisms which had lived in the brackish water, and the brackish clams died out almost completely, leaving only shoals (Fig. 10.) The 'Estuary of Death' had indeed proved worthy of its name. In addition, the constantly occurring counterflow causes organisms and sand to be carried towards the dam, and to pile up. Since almost all living creatures on the river bed died, there was no consumption of the organisms, and the material continued to pile up, rotting and creating a sludge (Fig. 11 on photo sheet). Straining the sludge shows that it is made up of nothing but refuse, in which no living organism can exist (Fig. 12 on photo sheet). A short time after the dam barriers were closed, an examination of this sludge showed large quantities of dead brackish water clam shells (Fig. 13 on photo sheet). In the adjoining Ibi River, which has no estuary dam, the continued existence of brackish water clam stands in stark contrast (Fig. 14 on photo sheet). According to the brackish water clam fishermen, the sand on the river bed of the Nagara River used to be very fine, making the area the best place for brackish water clam to breed. The sludge at points reached 2m depth. The Construction Ministry refused to acknowledge this as sludge, recording it as 'silt' instead. Silt is defined by the size of the particles of sand and soil. Nothing, however, can be deduced regarding the makeup of the material from the particle size. It is necessary to also record the fact that there is no oxygen, and that the matter includes large volumes of organic materials in a rotten state. In defining this state, NGO members chose to use the expression 'sludge'.

3-3-2-2 Increase in marshiness.

Close to the source of the Nagara River, the concentration of phosphorus is 0.01mg/l, which is very low. It increases as the river flows downstream, but is still under 0.02mg/l by the time the river reaches Gifu City. The increase is marked beyond Gifu City, and at the estuary area is 0.05mg/l. The concentration of nitrogen changes in a very similar way to that of phosphorus, and in comparison with the central area where the concentration is 0.5mg/l, the estuary area has a concentration of as much as 2.0mg/l. These concentrations exceed those of Lake Biwa, and are equal to those of Lake Suwa, which is known for being extremely eutrophic (Fig. 15, Murakami et al. 1994 survey). Waste water from Gifu City and its surrounds is collected into Arata River and Sakai River, and these empty into the Nagara River at a point 35km from the estuary. As a result, the stretch from 35 to 30m from the estuary is the part of the river, which has always had the highest concentration of organic substances. This is diluted as it moves downstream by the addition of tributary river waters, which are comparatively low in organic substances, and cleaned further by the water-cleaning environment of the reed fields etc.

This current has now been forced to stagnate by the introduction of the estuary dam. Between spring and autumn, repeated algae outbreaks occur, and on some days chlorophyll a levels were recorded at over 80_g/l (Fig. 16, Murakami et al.). Previously, when there had been a flow of water through the area, the normal recorded level was that of a few _g/l. The first ever-recorded case of waterbloom was seen on the Nagara River. In the summer, thermoclines formed, and water containing oxygen cannot sink to the riverbed, so that the oxygen levels at the riverbed are low, and marsh-like phenomena have increasingly been noticed. The Construction Ministry stated that there was no threat of this happening, but "the prediction" came off.

In time, sludge began to build up in the areas upstream of the dam too (Fig. 17 on photo sheet). The incidence of methane gas increased sharply from autumn to spring (Fig. 18 on photo sheet). Additionally, the reed fields, which were habitation for many animals, and which provided such an important natural cleaning function for the river water, did decrease in 100ha from approximately 300 ha by the construction of dam and connection. Also, it continuously is being destroyed after operation (Fig. 19, 20 on photo sheet and 21). Besides this, the incidence of the destructive insect chironomid, which is the source of allergic reactions, has increased exponentially (Fig. 22).

3-3-2-3. Obstacles to the passage of migratory fish.

With no dam on its main river, the Nagara River was one of the few limpid rivers up which the natural Rhododendron lateritium trout (smolting-type dwarf rill trout) was able to climb. It sustained enough fish for professional fishermen to make a living from it. As soon as the dam operations had begun it was acknowledged that there was a delay in the climbing of the river by the trout. A delay of around 2 weeks would not normally cause a huge amount of concern, but once the fish arrived, the catch statistics confirmed that there had been a huge fall in numbers. Fig. 23 is the Construction Ministry's published figures for the successive numbers of fish caught in the 38km area. It shows a steady yearly decrease. The point at which the graph shows a particular split is between the first half of 1995 (the year the dam went into full operation), when there were 7 fishing areas in which professional fishermen were working, and the latter half of 1996, when the current had disappeared, and drift net fishing had become impossible, putting most of the fishermen out of business. The 38km site became the lowest point for drift net fishing, and even there it was almost impossible. According to a survey of people by Niimura, Y., in 1994 the area downstream of the 38km point had a recorded catch of 4650 fish, which in 1999 had dropped to one sixteenth of the amount, 278 fish. It cannot be long before the Rhododendron lateritium trout stop climbing up the river altogether.

The catch of sweetfish had in the past far exceeded the numbers of fish released into the river, and the differential was always considered to be caused by the volume of naturally occurring sweetfish coming up the river. From 1995 onwards, with the beginning of the dam operations, both figures reversed, and the natural sweetfish were totally lost (Fig. 24). The large flooded area was also proving an insurmountable barrier for sweetfish heading down to the sea. The density of young sweetfish dropped to 1/5 up to the estuary dam, and the average age rose to over 13.4 days (Koya et al, 1997).

In the 'Response', the Construction Ministry stressed that the larvae of eel (=shirasu) would be able to climb beyond the dam, but "shirasu" eel fishing was destroyed (listening comprehension from fishermen).

Ropes were provided for the Eriocheir to climb, but numbers have descended year after year. Palaemon fishing has almost been destroyed (listening comprehension from fishermen). Sesarma have reached the point where nothing is seen of them other than older individuals. Professor Wada stressed (at the "round table discussion") that they would be able to climb the fishways, but the migratory fish who live on the river bed (Cottus pollux andCottus kazika) have been destroyed to such an extent that they are no longer seen in the river (Fig. 25). In contrast, black bass (Micropterus salmoides) and bluegill (Lepomis macrochirus) are increasing.

3-3-2-4 Changes in wild bird life.

From the year after the commencement of the estuary dam operations, there was an increase in numbers of some of the ducks such as Anas poecilorhyncha, Aythya ferina and Anas penelope. Aythya fuligula increased sharply in the year after dam operations began, but subsequently have dropped sharply (Fig. 26, Kumazaki,A & Ohtsuka, Y). This appears to have been caused by the disappearance of an environment, which sustained the bivalve shellfish, which the Aythya fuligula fed on. Acrocephalus arundinaceus, which lived in the reed fields, have also declined sharply.

3-4.　 Influence to sea area

Short-necked clam numbers have declined at the sea area near the river mouth of Nagara River (Fig. 27). Also, the prediction of Construction Ministry was completely mistaken.

4. Negative effects on the fishing and tourism industries.

4-1. The fishing industry.

4-1-1. The destroyed brackish water clam fishing industry. Although brackish water clams cannot reproduce in fresh water, they can live there, and so the Akasuka Fishermen's Cooperative were bringing brackish water clams from the Ibi River, and releasing them in the Nagara River upstream of the dam, to harvest later. There were also many brackish water clams left in the Nagara River from before the closure of the dam barriers, and so clam fishing was still possible (Fig. 28 on photo sheet). Indeed, it seemed for a while that it was thriving, as freshwater clams, which had previously only been able to exist further upriver, began to reproduce in the formerly brackish water area. The brackish water clam numbers began, however, to decrease, and eventually even the clams introduced from the Ibi River could not be caught any more. Freshwater clam numbers have also declined sharply. The riverbed has become covered in refuse, and is not the sort of environment, which could support clam any longer (Fig. 29 on photo sheet, data from "Clam project in Kuwana"). The condition of the area downstream of the dam is as noted above. There has been sand spread in an area approximately 4km from the estuary, on the left shore, which has been designated as a 'beach plan' area by the Construction Ministry. Brackish water clam and hard clam have also been introduced here. Taxpayers money has been spent in order to bring enquirers to this area and show them that 'the riverbed has not turned to sludge. It is a sand bed, and there are brackish water clam living here.' Not only has a manufactured sand bed, which covers less than 1% of the whole area, been created in order to cover up the sludge problem, but this has been done with taxpayers' money, adding insult to injury, and making it a doubly criminal act. The Construction Ministry has repeatedly stated that 'there has been no damage to clam fishing in the 3 Rivers of Kiso.' In one way this is true. The 3 Rivers of Kiso include the Kiso and the Ibi Rivers, which flank the Nagara River. There are no longer any clams fishermen working the Nagara River. These fishermen now eke out a livelihood by spending far longer periods of time traveling to either the Kiso or the Ibi river, and fishing for their clam there. The '3 Rivers of Kiso Clam Fishing Statistics' are the Construction Ministry's way of making fools of the fishermen, and deceiving the nation.

4-1-2 Rhododendron laetirium trout fishing.

In the lower river regions, a survey was carried out among fishing cooperatives. The number of people who replied that they thought the amount of fish to be caught had dropped substantially was 52%, and when the number who thought it had dropped slightly are included, this figure reaches 73%, showing that a high proportion believe the numbers of fish in the river has fallen. 35% believe that the fish have become significantly later in their climbing up river, and a further 31% think that there has been some delay.

4-1-3. Sweetfish fishing.

The Nagara River used to be known as the Mecca of sweetfish fishing amongst those who enjoyed this sport. The sales figures for yearly fishing passes from the 3 Nagara fishing cooperatives (Nagara, Nagara Central and Gujo) after the dam began operation, however, have dropped sharply, recording a loss.

In a survey done among fishing cooperative committee members in the central region, 90% responded that they thought fishing conditions had worsened over the last 10 years. As a reason for this, 137 people out of a total of 182 gave the fact that naturally occurring sweetfish had stopped climbing upriver. When asked about the level of the decline, 32% stated that they believed the numbers had fallen by over 90%, and adding the number of people who thought numbers had fallen by between 50 and 90% takes the total to 90% of respondents (Fig. 30).

Surveys among the fishing cooperatives in the lower river regions also produced similar results. 91% responded that the numbers of fish had dropped, of which 63% believed that it has dropped significantly. 75% also replied that the fish have been climbing up river much later.

4-1-4. Eriocheir fishing.

According to official fishery statistics from Gifu Prefecture, the amount of Eriocheir caught in 1998 was 0.8 ton, a sharp drop from the almost 1.5 tons caught in 1996. In comparison, the amounts caught in the Kiso and Ibi Rivers during the same period showed no decline.

4-1-5 Shirasu Eel fishing

Shirasu eel fishing flourished formerly at the Nagara River estuary. It was not unusual to hear of fishermen who would make hundreds of thousands of yen from one night‘s fishing. After the dam began operations, there were some years in which shirasu eel were able to populate the area downstream of the river, but now shirasu eel fishing has died out completely (listening comprehension from fishermen).

4-2. Destruction of tourism.

4-2-1. Cormorant fishing.

Nagara River's Cormorant fishing, by the cormorant fishermen of the Imperial Household Agency, which has been carried out on the river for 1200 years, has declined sharply (Fig. 31). The hotels in Gifu City, which are located along the banks of the Nagara River, have been forced, one by one, into closure (note 3). There is no attraction in watching the cormorant catch and swallow sweetfish which are no bigger than a few centimeters in length. Sweetfish of 20, sometimes 30 centimeters glowing on an open fire has become a sight of the past. The flavor of the fish, which was the lifeblood of the tourism industry, has also inevitably been lost. The cormorant fishermen see their living fading away. There is still no one involved in the tourism industry who has been able to express opposition to the 'approval for the Estuary Dam' granted by the 'Prefectural Office'.

=note 3=

Hotel Nagarakann, Hotel Hakuunnsou, and Nagaragawa Hotel were closed 7 years ago, 4 years ago, and at 2,000, respectively. Renaissance hotel is under discussion for closing.

4-2-2 Visiting fishermen

It is feared that the decline in visiting fishermen will have had a negative impact not only on the shops, which sell fishing tackle and decoy sweetfish for angling by decoy, but also on accommodation and tourist facilities in the area.

5. Fears surrounding the newly generated drinking water.

5-1. Diversion to tap water.

In the five years since the dam was opened, there has been absolutely no new demand for industrial water supply. In order to stem criticism that the dam was a meaningless facility, and to avoid having to reopen the barriers, in April 1998 the Construction Ministry began to divert the water into tap water supplies of 5 cities and 5 towns in the Chita Peninsula. This required carrying the water across the Kiso River. In addition there was an allocation of 0.732t/sec supplied to 2 cities and 8 towns in the Central Ise Water Supply area, and water supply to North Ise area was also begun. The waste of the dam has been compounded by the wasted expenditure on new water supply facilities.

5-2. Fears surrounding the tap water.

Tap water in the Chita Peninsula has been described as 'foul-smelling' and 'having a sharp taste'. There is a movement in progress campaigning to have the water supply returned to its original source, the Kiso River. Since the estuary area receives wastewater and sewerage, causing an environment in which algae can occur, the estuary water contains many elements which make it highly dangerous for use as drinking water.

5-2-1. Carcinogenic toxins.

The toxic mycrotisitin, which is in the waterbloom-forming algae, and trihalomethane, which is generated by the chlorinating of water containing organic substances, have both been shown to be carcinogens. There is epidemiological data to show that trihalomethane is also related to stillbirth. This data cannot be ignored.

5-2-2. Infectious diseases.

Normal chlorinating cannot kill off Cryptosporidium protozoa, which cause epidemic diarrhea when allowed to contaminate tap water. There is no known cure for this condition, and people with low immunity who contract this condition may die from it.

5-2-3. Chemical substances which interfere with reproductive organs.

It is now common knowledge that certain chemical substances known as environmental endocrine disrupters are present in the downstream areas of almost all rivers. These substances have been shown to have a destructive influence on the reproductive organs of humans. According to the Construction Ministry's survey, water collecting above the Estuary Dam in the Nagara River had the highest levels of adipinic acid di-2-ethylhexyl in the country. In addition to this, our research shows that active substances, which react with the estrogen-hormone receptor, are also present (Fig. 32). It is surely beyond conscience that water containing such inevitable dangers should be presented as drinking water.

6. Verification of profitability of water use.

Northern Ise's industrial water supply has an allocation from Kiso River too, of 0.9t/sec, and its actual water use is under 1.16t/sec, or 100,000 tons per day. The water supply from Nagara River only becomes unstable at the high tide upper limits during low rainfall, or drought periods. Irrigation water for Hashima City, Kaizu Town and Hirata Town has to be taken from a point at which there is no seawater influence. Taking into consideration the points raised in 5-2, if irrigation and tap water for Nagashima Town was to be switched over to a supply from Magai on the Kiso River, any benefit from the use of newly provided water would be almost completely negated.

7. Verification of flood control effects.

7-1. The Nagara River Estuary Dam is not a flood control facility.

The Construction Ministry finished dredging the Mound as soon as possible, having waited for full operation of the dam to begin, despite having insisted that it presented no threat of a flood. From this point, the purpose of the dam as a flood control facility was wiped out. At present the one and only function of the dam is that of tide control. In the typhoon on 15th September last year, the riverbank of the upper reaches of the Nagara broke, and the Construction Ministry defended itself by saying that the 'effects of the dam' did not extend to the upstream areas. There may possibly have been some benefits from dredging the Mound in that it was possible to drain floodwaters safely, but there is no flood control mechanism incorporated in the dam itself. On the contrary, it in fact hinders the downward flow of floodwater, and causes the high water that comes from the sea to rebound on itself, increasing the danger of damage to the bank. It is important to stress that the dam has no flood control facility.

The designated floodwater discharge volume was revised to 7,500 cubic meters / second in 1963, and at the same time, the riverbank was judged not to be high enough. These factors were the reasons behind the dredging plan. The 25-30km area, which was where the dredging was said to be most effective, was shown however to have a natural bank height equivalent to the space required to allow a current of 7,500 cubic meters / second, that is 1.85 _ 2.10m. The area in which the riverbank is most under threat is that between the north end of Nagashima Town and the south side of Kaizu town. Here, there is only a space of 60 _ 80cm. The effect of dredging on this area is limited to around 50 _ 70 cm, and there needs to be raising and strengthening of the embankment additional to this. As can be seen from this example, the question must be asked whether dredging has had any effect in flood control at all.

8. Project enforcement _ Background.

8-1. Decision-making powers regarding Public Works.

The decision-making authority regarding public works rests with the Cabinet. In reality, though, the agreement on such issues is usually reached behind the scenes before the Cabinet meeting occurs, and the eventual passing of the project is mere rubber-stamping. Effectively, the bureaucrats from each ministry and agency make decisions without ever having to come before the public eye. In 1995, as an attempt to crack down on abuse of the system, a cross party 'Diet Members' Committee for Checking Public Works' was formed, and the 'Public Works Control Law' was put forward. Currently frameworks are being put in place to ensure that Diet members check public works.

8-2. Environmental assessment.

In 1963 the Kiso 3 Rivers Estuary Resources Survey Group was formed, as a precursor to the building of the dam, to investigate economic fish resources only. In response, in 1991, university researchers from universities across the Tokai region (Aichi, Gifu and Mie Prefectures) produced a 'Request for temporary halting and environmental assessment of the Nagara River Estuary Dam building project'. This was presented to ministers and prefectural governors.

8-3. Lies and euphemistic predictions.

To compound the fact that the estuary dam made no contribution to flood control, and showed no benefits in terms of new water supply, it has caused immeasurable environmental damage. This sort of self-justification of public works has become an accepted part of our nation's governmental policy on construction. Even Environment Agency gave no serious consideration to effect on the environment, and euphemistic predictions were woven in order to allow the government to wriggle out of the situation. Following the commencement of operations of the dam, the Construction Ministry pushed through a 5 year monitoring program, with an exceptionally large budget of 5 billion yen. This monitoring committee, however, closed on 3rd March of this year, without ever carrying out an evaluation of the environmental impact.

9. Towards recovery of the ecosystem.

9-1. The operation of the dam and recovery of the ecosystem.

9-1-1. Controlling the buildup of sludge.

The buildup of sludge is the main cause of the destruction of all life on the riverbed, as the organic substances which feed the benthos that live there disappear due to the low oxygen levels. The release of the sea water layer would be effective as a countermeasure. One way to achieve this would be to allow seawater to flow upstream at times where there is a strong mixing, such as at the high tide of spring tides. Additionally, in order to stop the counterflow in the lower layer at ebb tide of neap tide, the gates need to be opened then too.

9-1-2. Regeneration of Brackish Water Clam fishing.

As a result of the dam's operation the riverbed has become totally unable to sustain brackish water clam, and an immediate recovery of suitable conditions cannot be hoped for. If there was a large release of water to the levels seen on 15th September 1999 (approximately 5900 tons/sec), the sand beds could recover, and subsequent to this clams could be reintroduced from the Ibi River. It could safely be assumed that they would repopulate the riverbed under these conditions. Also, brackish water clams are made to be the fertile if it allows going up the seawater to the upstream of the dam for egg-laying season.

9-1-3. Reintroduction of migratory fish.

Migratory fish pass through the brackish water area throughout the year (Fig. 33). If, however, the gates were completely opened, or operations could be continued with the gates at an almost open position, during the upstream and downstream migratory seasons for sweetfish and rhododendron laeterium trout, these and other fish who migrate through the brackish water at these times, including Cottus could be expected to repopulate the river relatively quickly.

9-1-4. Recovery of the reed beds, and countermeasures for the chironomid.

If the dam was completely opened, or operated in an open position, the water level would drop by more than 2m at maximum. This would give suitable conditions for reeds. With some replanting, it could be possible to see a recovery of around 100ha in around 10 years. On the other hand, the upstream flow of seawater would limit conditions for chironomid larvae. Chironomid larvae have in the past been controlled by methods including releasing carp or crucian carp, or by hormone spraying, but a saltwater counterflow is in fact the safest and surest countermeasure. In this case, only types with salinity resistance can survive, and chironomus yoshimatui and einfeldia, which tend to occur in huge volumes, will die off.

9-2. Salt damage monitoring.

Is there really a need for such expensive and noxious facilities in order to stop salinity and salt damage? There should be a full scientific discussion on this subject. There is a possibility that salt water could seep into underground water, but there is no threat of salt water crossing the clay layer from below and entering farm areas (personal communication from Okuda, S., a member of monitoring committee). Additionally, running fresh water for farming from upstream, and building water channels along the riverbank, provide multiple cheap countermeasures for salt damage. There is a need to monitor salt levels in soil and water channels as a result of opening the dam gates, and collect enough data to be able to lower salinity levels at flood tide of neap tide by operating the gates as submerged weir.

10. Management of the flooded area.

10-1. Recovery of the swamp.

Potential salt damage to fields caused by opening the dam barriers can be offset by compensation. Out of 900-1000ha of land, the amount suffering salt damage after the Ise Bay Typhoon in 1959 was only 20-40ha, and since then salt damage has been restricted to a very limited area. Calculating at the same, rather unlikely, levels of damage, the amount of compensation needing to be paid to farmers in Takasu would be 12 _ 14 million yen per year. Alternately, the areas, which are considered to be in such danger, could be purchased, and used in the regeneration of the swamp.

10-2 Securing the flood plain

The towns between the Nagara River and the Ibi River, namely Anpachi, Wanouchi, Hirata and Kaizu, and those between the Nagara and Kiso Rivers, namely the southern part of Hashima City and Nagashima town, are basically flood plains, and historically have prepared for floods by making fortifications. As the embankments were strengthened, and safety measures improved, more and more people moved into these towns. However, if the embankment is strengthened to the extent that it can stand up to a once-in-a- hundred-years heavy flood, it may still give way in the sort of flood that could occur once in 150 years. The stronger these embankments are made, the larger and more serious potential flood damage becomes. The need for some sort of response to this flood plain issue is starting to become a serious problem. The most important public facilities belonging to the area are should be surrounded by embankment. In other areas, dwellings have been built on stone walls, and boats are kept on hand, to allow effective response to a flood, should it happen. Insurance and compensation could cover the damage, which a flood could potentially cause. These practical responses need to be given careful consideration in the current climate.

10-3 Changing water intake over to a more upstream area.

The North Ise Industrial Water Supply should be changed over to a source further upstream, where the water is not salty. If this was achieved, the dam could be opened, or operated in a nearly opened state.

10-4 Safeguarding the purity of drinking water Water supplies for drinking water should not be taken from the estuary area, but should be compulsorily changed over to a more midstream or upstream area. This should be accorded the highest priority.

Hold development associated with upstream ski resorts, golf clubs, and lumbering of forests. Not cared Japanese cedar (Cryptomeria japonica) forest and Japanese-cypress (Chamaecyparis obtusa) forest should be felled in order to make the deciduous broad-leaved forest band. 2 25