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Press Release

FY 2002 Nationwide Survey on Aquatic Life Forms

August 8, 2003

The nationwide survey on aquatic life forms for FY 2002 was conducted with the participation of approximately 92,000 people, a record number for this survey. According to the survey results, which were compiled by the Ministry of the Environment and the Ministry of Land, Infrastructure and Transport:

-    Water quality evaluations were conducted at 5,141 survey points nationwide by means of surveys of aquatic life forms found in the rivers. Survey points deemed to have clean water comprised 56% of the total.
-    The survey had participatory support from a large number of schools and civil groups, with most participation taking place during summer vacation (73% of participants were affiliated with elementary or junior high schools and 24% of participants were affiliated with local children's organizations or civil groups).

Insofar as river water quality is reflected in the population status of aquatic life forms such as sawagani freshwater crabs, kawagera water flies, and other river dwellers, it is possible to determine water quality by using these creatures as indicators. One benefit of this kind of survey is that it is simple to understand and no expensive equipment is required, making it easy for anyone to participate. Furthermore, becoming closer to nature through this survey enhances people's interest in environmental issues, and thus the Ministry of the Environment and the Ministry of Land, Infrastructure and Transport have been conducting this nationwide survey on aquatic life forms annually since FY 1984.

The Ministry of the Environment is developing a system by which participating groups and individuals can input their survey findings directly via the Internet and then view the results immediately afterwards. This system will be officially launched in FY 2004 (available only in Japanese).

Overview of the FY 2002 Survey Results

1.   Survey methodologies

Thirty species of river-dwelling aquatic life forms were selected as target creatures for this study. Criteria for selection were that (i) the creatures are found throughout Japan; (ii) the creatures are easy to classify; (iii) the creatures have a high degree of usefulness as indicators of water quality. Creatures were collected from various rivers and identification and classification was conducted for creatures selected as water quality indicators. Each survey point was assigned on a four-tiered scale, with a rating of "I" indicating "clean water," "II" indicating "slightly dirty water," "III" indicating "dirty water," and "IV" indicating "extremely dirty water."

2.   Survey results

(1)   Number of participants

FY 2002 saw the participation of 91,649 people (compared to 87,450 people in FY 2001), the greatest number of participants thus far.

  Number of
Number of
participating groups
Number of
survey points
Total 91,649 2,495 5,141
Class 1 rivers*1 16,146 588 615
Other rivers*2 75,503 1,907 4,526
Notes:    1.   Class 1 rivers in areas under the direct administration of the Ministry of Land, Infrastructure and Transport.
    2.   Class 1 rivers under the administration of the prefectural government, Class 2 rivers, etc.(rivers other than 1 above).

(2)   Water quality assessment results

In FY 2002, 56% percent of survey points were evaluated as having clean water, representing a decrease of 5 percentage points from the previous year, when 61% were judged as having clean water.

  Total Class 1 rivers Other rivers
I Clean water 56% 53% 57%
II Slightly dirty water 27% 35% 25%
III Dirty water 12% 8% 13%
IV Extremely dirty water 3% 2% 3%
Note:    Numbers may not add up to 100% due to rounding.

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