Water / Soil / Ground Environment

State of Japan's Environment at a Glance: Japanese Lake Environment (1996)

Water Quality Bureau
Ministry of the Environment

Japanese Lakes

Japan's major lakes (one hectare or larger) comprise a sizable area of 2,380 square kilometers (0.63% of Japan's land area). Excluding Biwa Lake, large natural lakes in Japan are distributed in the central and northern regions. These "open water bodies" are customarily called lakes, ponds, lagoons, or seas but do not have clearly defined classifications. In addition to these natural lakes, many large-scale artificial lakes were constructed after the Second World War.

(Remote-sensing imagery was made available
by courtesy of the Tokai University
Research and Information Center)


Origin of Lakes
The Importance of Lakes
  • Lakes as a Water Source
  • Lakes for Fishing
  • Lakes as Tourist and Recreation Locations
  • Lakes as Conservation Areas for Biodiversity
  • Lakes as Natural Balance Preserving Reservoirs
The Central Issue - Eutrophication
Deteriorating Lake Environments
  • Changes in Lakeshores
  • Invasion of Exotic Species
Efforts Toward Maintaining Water Quality
  • Environmental Quality Standard
  • Water Pollution Control Law
  • Law Concerning Special Measures for Conservation of Lake Water Quality (Clean Lakes Law)
  • Measures for Other Lakes
A Solution with Multiple Measures
Basin Management Measures
  • Sewage System Installation
  • Small-scale Wastewater Facilities for Rural Communities (Rural Sewage Systems)
  • Integrated Septic Tank Treatment System for Domestic Wastewater
  • Measures for Wastewater Discharged from Factories or Other Facilities
  • Measures for Agriculture, Livestock, and Fishing
In-Lake Cleaning Measures
  • Diversion
  • Water Conveyance (Dilution)
  • River Water Improvement
  • Promotion of Aeration and Water Circulation
  • Managing Water Weeds, Water Bloom, and Algal Bloom
  • Dredging
  • Ecosystem Conservation
Community Responsibility for Lake Clean-up
  • Taking Care of Household Wastewater
  • Cooperation in Upper and Lower Reaches
  • Educating the Next Generation
  • Citizen Participation
  • Lake Research
  • International Cooperation

Water Quality Management Division, Water Quality Bureau,
Ministry of the Environment

Address: 1-2-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8975 Japan

Tel: +81-3-3681-3351 Fax: +81-3-3501-2717

International Lake Environment Committee Foundation (ILEC)

Address: 1091 Oroshimo-cho, Kusatu-city, Shiga 525-0001 Japan

Tel: +81-775-68-4567 Fax: +81-775-68-4568