Messages from Departments and Centers of NILIM

Direction of effort responds to environmental
restoration of Tokyo Bay
SUZUKI Takeshi (Dr. Eng.)
Director of the Coastal, Marine and Disaster Prevention Department(Keywords) Coastal area, environmental restoration, Tokyo Bay
1. Introduction
Since Japan’s coastal area has large population andeconomic accumulation, large amounts of human sewage
is finally discharged into the coastal sea. And thecirculation of sea water is not enough in the enclosed sea.
Consequently, red tides are chronically generated byeutrophication, and dysoxic water masses are formed byaccumulated organic bottom sediment, having serious
effects on aquatic fauna and flora, and other water
environment issues.
“Environmental Restoration of the Sea“ has been
established for the urban restoration project at the thirddecision in December, 2001 to remedy those coastal
water environment issues. In response to this, Japan
Coast Guard (JCG), Ministry of Land, Infrastructure,
Transport and Tourism (MLIT), Ministry of theEnvironment (MOE), Fisheries Agency and relevant
local government formulated “Action Plan for Tokyo
Bay Restoration“ in March, 2003. In March, 2013 it will
have been 10 years since “Action Plan for Tokyo Bay
Restoration“ was implemented.
Tokyo Bay is close to nature sea area that is located in
the center of the Metropolitan area. The coastal area andwatershed are population and industry intensive and thecenter of urban and industry that drive the Japaneseeconomy. The size of the Metropolitan area (covering 4prefectures) is 14,000km2 which is only 4% of the total
landmass, but its population is 3.5 million (28% of thetotal population), and the industry ships for more than
47 trillion yen (18% of the national revenue).
2. Past efforts of Tokyo Bay Restoration
The purpose of “Action plan for Tokyo Bayrestoration” is to “Creation of “Tokyo Bay” that fits theMetropolitan area by retrieving amiable and beautiful“Sea“ that is diverse with wildlife and with comfortablywater to play with”. 3 section committees: (1) Land areaload reduction, (2) Environmental improvement in sea
area, (3) Monitoring of Tokyo Bay, had been establishedand has made progress towards the goal achievement.
Effort items of each section committee are given inTable-1.
Table-1

Effort items of each section committee.

Sectioncommittee
Landareaload reduction

Environment
improvement
in sea area
Monitoringof Tokyo Bay

Effort item
① Implementation of total amountreduction project and efficient businessmeasures to reduce pollution from land.
② Construction and improvement of
sewage facilities, and spread of advanced
disposal processes. ③ Efflux load
reduction in the rain. ④ Cleanup
provision of river. ⑤ Reduction ofpollution from ground surface. ⑥
Collection of floating debris.
① Pollution reduction in sea area. ②
Improvement of cleanup efforts of seaarea.
①Enhancement of monitoring ②Shareand effective use of monitoring data ③
Civilian Monitoring activities

If you look at the efforts in the sea area, there is“Pollution reduction in sea area”, removal of mud
including sedimentary organics in canals, improvementof bottom sediments, development of shallow bottom byusing good sand, efficient collection of floating debris on
the sea surface by cleanup vessels, collection of seabeddebris by NPOs and fishermen, cleanup activities of thebeach and tidal flats, and all of these have beenconducted.
Regarding “Improvement of purification ability of seaarea”, conservation of existing tidal flats and seaweed
beds, rehabilitation / development of tidal flats, shallow
bottom, beaches and rocky fishing spots, formation of
biological network in a standpoint of a long period,
construction of port structures that promote biofuels,
reconstructing of mildly-sloped seawalls towards thecreation of habitats for benthic organism, backfill ofdeep digging traces in the past that is an occurrence
factor of blue tide, and these have been accomplished.
Regarding Monitoring of Tokyo Bay, enhancement ofMessages from Departments and Centers of NILIM
monitoring about bottom layer DO and benthicorganisms, reinforcement of monitoring of tidal current
and water quality by monitoring posts and marine
vessels, development of website with relevant
information, survey on beach litter and beach cleaning
by local residents, reinforcement of cooperation withcitizens and NPOs that do environmental conservation
activities in Tokyo Bay, and all these have beenaccomplished.
3. Direction of Effort towards Tokyo Bay Restoration
Tokyo Bay restoration is not a goal that can beachieved by accomplishing entirely new efforts in a shortperiod. Therefore based on previous improvement efforts,technology and knowledge, by making proper choices,improving, adding new efforts, and carrying on
traditional efforts will be a realistic approach.
The effort towards Tokyo Bay restoration needs to set
the overall goal. The goal should be attractive andhopeful that we can have hope towards the future.
It is impossible to set such a goal that is viable fromevery side such as the technical aspect, the economicaspect and the social aspect. Therefore when efforts areactually implemented, a goal cannot be set with only
thinking of one accomplishment of the overall goal.
Where it is implemented, it is possible to thinkspecifically of contents, constraint conditions and othergoals of the implementation. Thus collecting informationby all possible means, firmly considering, setting goals
that are realistic and viable despite the possibilities ofcertain uncertainties, and implementing are needed.
Today, the Japan economy is in a tough situation.
Therefore financial constraints for the efforts of Tokyo
Bay restoration has to be considered, and it is important
to improve the environment efficiently through alow-budget. In this situation, multipurpose utilization ofport facilities, use of dredged soil and recycled material,
making improvement of the water quality efficient, andthese kinds of efforts are important. The cooperation byvarious agents to advance those efforts will be needed,
but to do that, approach that does not lose possibility by
a formalism “Relaxed cooperation based on ability”
should be emphasized.
4. Conclusion
The “Environmental Restoration of the Sea” project
was started in December, 2001 as part of the urban
restoration project, and during the past 10 years efforts

have been made towards achieving it.
Technology and information gathering in regards to the“Environmental Restoration of the Sea” have advanced,
but it is a large goal that is not easily accomplished.
Turning Tokyo Bay that is located in the middle of themetropolitan area into an area that is considered valuablewith comfortable nature and biological production can
only be beneficial to Japanese economy and society.
It is an extremely difficult goal to have, but wrapping
your head around it, increasing knowledge, advancing
technology and not giving in to the challenges of thegoal are necessary.

overall goalThink overall goal
and implementation
goal separately.

 problem is complicated Lack of information
 A lot of uncertainties
 End up with setting up
higher goal

implementation goal Content is specific Possible to consider
specifically relevant
constraints
 End up with setting up
realistic goal

Figure-1 Two goals

Multipurpose use ofport facility

Toughsituation ofnational
financeCooperation ofvarious agents• Relaxed
cooperation basedon ability• Symbiosis
organism seawall• Symbiosis
organismbreakwater

Active use ofenvironment andecosystem• Calm with scenery• Fishing andClamming• Improvement offishery production• Let it tie toeconomy

Effective use ofdredge soil andrecycle material• Development oftidal flat andseaweed bed• Filling deep
digging trace• Improvement ofbottom sediments
Making water quality
improvement
efficient• Debris pickup• Control of influx
load

Figure-2 Direction of effort towards restoration of sea