1. Recreational use of river terraces 2. Revetment harmonious with a river's environment 3. Improvement of reservoir water quality 4. River purification projects 5. Water quality improvement vessel 6. Biological index of water quality in Japan [video cassette] 

 - Japan  [date of publication not identified] 
 - 1 videocassette (60 min.) : sd. , col 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Ricers--Japan.<br/>Water quality--Japan.