Lake Water Quality Conservation
Measures of Japan
December 11, 2019HASHIMOTO Tsubasa
Deputy Director, Water Environment Division,
Environment Management Bureau,
Ministry of the Environment, Japan1

Current state of lake water quality and pending issues in Japan
Wastewater regulation, better sewerage, and other measures have, to some extent, reduced theinflow load of nitrogen and phosphorus and improved water quality in lakes, but there is need forfurther improvement because it has been harder to meet environmental standards in lakes than inrivers.
Naturally derived nitrogenand phosphorusPrecipitation, etc. ＮＯｘ

Chemicalfertilizers & feed

Waste treatment

Reduced fertilizer
use policies

Groundwater infiltration

Place-of-businesswastewater

Domestic
wastewater

Sewage treatment Wastewater regulation

Nitrate nitrogen

Domestic
wastewater

Accumulation, nutrient build-up
Urban effluent
Road cleaning

Eutrophication

Food & raw
materials

Removal of nutrient salts fromcirculation by mowing and fishing,etc.

Lake bed accumulation & elution into lake water
Algal blooms, putrefaction odors, damage to water quality and poor bottom layer oxygenationMinistry of the Environment2Trends in meeting environmental standards (BOD/COD)♦ Among standards for protecting the living environment of the people, organic pollution
standards (BOD and COD), overall, have gradually tended to be better met.
♦ While standards in rivers are now generally met, in lakes, bays, inland sea areas, and otherenclosed bodies of water standards remain poorly met.
Rivers: 94.0 %Samples meeting
standards (%)

Sea areas: 78.6 %Ministry of the Environment

Lakes: 53.2 %Year3Framework of measures for water environment improvement in JapanTarget

Measures forindustrial
wastewater

Establishment of Environmental Standards on Water Quality(Basic Environment Act)

National Government

・Establishment of effluent standards (Water Pollution Control Act)
Uniform national standards

National Government

・More stringent effluent standards (Water Pollution Control Act)
Local governments
・Regulations for private companies (Water Pollution Control Act)
Measure, log and and notify effluent pollution status, on-site inspections→ Penalties, order for remedies, other administrative guidance

・Investment in pollution control
・Efforts such as Human Capacity Development
Measures fordomesticwastewater・Construction of sewerage (Sewerage Act)・Installation of Johkasou(Johkasou Act ) etc.

To formulate a “Plan for conservation of lake water quality” of each

Measures for conservation
designated lake in accordance with the Special Measures Act for Conservingof lake water quality

Private companies

National and local
governments, Individuals

Local governments

Lake Water Quality (Lakes Act) and implement the conservation measures

Ministry of the Environment

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Act on Special Measures concerning Conservation of Lake Water Quality
Because lakes are enclosed bodies of water, water quality conservation in lakes requires measures more advanced thanthose in the other water bodies.
Special measures, in addition to the regulations provided in the Water Pollution Control Act, are being taken in the lakes
designated in accordance with “Lakes Act (Act No.61 of 1984).”
Policy for the Conservation of Lake Water Quality(The national government selects lakes for the designation from all lakes in Japan)
Governors of prefectures request the Minister of the Environment to designate lakes and areas(11 lakes including Lake Kasumigaura)

11 designated lakes in Japan
Kamafusa Dam Reservoir (Miyagi)
Lake Hachiro (Akita)

Lake Nojiri (Nagano)
Lake Suwa (Nagano)Kasumigaura(Ibaraki, Tochigi, Chiba)

Lake Biwa (Shiga, Kyoto)
Nakaumi (Tottori, Shimane)
Lake Shinji (Shimane)

Inbamuna (Chiba)
Teganuma (Chiba)
Lake Kojima (Okayama)
Ministry of the Environment5Lake Water Quality Conservation Plan (Lake Plan)
Lake Water Quality Conservation Plan foreach designated lake
Formulated by local government, subject to approval by
the Minister of the Environment after discussion in Conference on
Environmental Pollution Control.

An example of effluent countermeasures area (SannoRiver Basin in Kasumigaura Catchment Basin)

Pollutant load regulation

In addition to concentration limits stipulated in the Water Pollution Control
Act, daily load limits set

Infrastructure implementation

Installation of sewerage, septic tanks, etc. and dredging, etc.

Designation of effluent countermeasures areas
Priority implementation of diffuse-source countermeasures

Regulations on structures for small-scale animalhusbandry and aquaculture in a lake and their use
Guidance, advice, recommendations to operators offacilities other than regulated facilities
Designation of protected areas around lakes

Conservation of lakeside plants that help to purify water (Notification
system for operations undertaken in areas around lakes)

Regulation of total amounts (when a further regulation is required)
Ministry of the Environment

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COD and inflow load in Kasumigaura
Kasumigaura COD

Kg/day自然系
Naturally derived
市街地系
Urban
農地系
Agricultural
畜産・水産系
Animalusbandry/fisheries
産業・工業系
Commercial andindustrial
生活系
Domestic
COD濃度(西浦)COD concentration （Nishiura）

1981198219831984198519861987198819891990

19911992199319941995199619971998199920002001200220032004200520062007200820092010201120122013201420152016

COD濃度(北浦)
COD concentration （Kitaura）

Note 1: The COD concentration in each lake is the average of the annual average COD concentrations observed at all water
quality examination points in the lake (4 in Lake Nishiura and 2 in Lake Kitaura).
Note 2: Since FY 2010, the load from chicken farms has been included in the animal husbandry and fisheries load. H net-cageaquaculture of carp resumed in the same year (no load from this activity in FY 2005).
Ministry of the Environment

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Experience from measures implemented in lakes in Japan and future direction of the measures
１ Water quality control in catchment basins for conserving lake environment◎ Accumulation of basic information through pollutant load monitoring, water quality monitoring, etc.

◎ Integrated implementation of wastewater regulation and measures for domestic wastewater with public works◎ Extension and improvement of diffuse-source countermeasures

２ Target setting and implementation, extension and improvement of measures
adapted to characteristics of lakes◎ Formulation of a plan specific for each lake・ To increase measures adjusted to characteristics of a lake (with a long-term vision, improvement targets andindividual indicators)[Examples of individual indicators] Transparency (Lakes Suwa and Nakaumi), evaluation in lake environment
survey based on human senses (Nakaumi, Lake Shinji)◎ Improvement of poor bottom layer oxygenation, prediction of effect of climate change, implementation ofadaptive measures to the change, etc.
３ Collaboration among people involved in lake water management and its promotion◎ Continuation of concerted effort by local governments managing lakes and people concerned with lakes(local residents, fishermen, farmers, educational institutions, etc.) for the improvement oflakeside environment

Ministry of the Environment8

Thank you for your attention.

Ministry of the Environment

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