without treatment. The nutrient disposal, mainly nitrates and phosphates, sim- 

 ilarly will be controlled. Conflicting evidence, coupled with lack of monitoring 

 type of information available from secondary sources, prevented the inclusion of 

 these items in the model. 



The level of aggregation used in the study at the industry level was to con- 

 sider one industry as one activity rather than taking each firm independently. 

 At the community level, villages were aggregated into one sector or land area 

 if they all occurred in the same region and in the same river basin. The city was 

 aggregated on the basis of the urban activity and taken up as urban activity, 

 rather than as individual sectors of the urban population and industry. The 

 location of economic activity and physical features were defined by dividing the 

 basin into areas and by natural or physical features. 



All information used was compatible among the secondary sources used and 

 converted to a 1967-68 time period for benefits and costs, and to 1970 for 

 cultural activities. 



