As river-flow level decreased, the small communities shifted to waste-water 

 disposal methods which reduced BOD discharged into the river. 



This shift is brought out in Table 5.2 for groups of industry. Each industry, 

 and industries as a group, shifted to waste treatments which were increasingly 

 effective in removing BOD as river-flow level decreased. Between groups of 

 industry, the change associated with flow level differed. Major changes in paper 

 and wool industries occurred in moving from high flow to median flow and for 

 tanning in moving from median flow to low flow. The optimal waste-water 

 treatment process in each industry changed, also. In the paper industry, the 

 type of treatment shifted from sedimentation primary, and irrigation secondary 

 at high-flow level to public treatment by activated sludge process at median- 

 and low-flow levels. In the wool industry, the optimal type of waste-water 

 treatment shifted from no treatment at high-flow levels to public treatment 

 with activated sludge at the median- and low-flow levels. In the tanning industry, 

 the optimal treatment shifted from trickling filtration to activated sludge, and 

 production levels were decreased slightly because of the low-flow conditions of 

 the river. 



In the urban sector, the appropriate waste-water treatment process shifted 

 from trickling filtration at high-flow levels to activated sludge at the median- 

 and low-flow levels. At low-flow levels, the river was an optimal source of most 

 of the urban water supply because the pre -use and post-treatments of this source 

 of water improved the overall quality of the river. Although this source of water 

 supply may be optimal from a basin standpoint, it is hardly optimal from the 

 urban (Keene) standpoint. 



In the rural sector, from a basin-wide standpoint, rural housing shifted from 

 no waste-water treatment to septic-tank treatment, when moving from median- 

 to low-flow river condition. Forestry production was not influenced by river- 

 flow level, but rather contributed to river-flow level through increased runoff 

 due to cutting of timber stands. In the agricultural sector, little change occurred 

 in optimal resource use between high-flow levels and median-flow levels. But 

 when moving from median-flow levels to low-flow levels, the optimal allocation 

 called for fewer dairy farms and for these fewer farms to employ more expensive 

 practices that pollute less. 



The influence of river-flow level on resource use was the common tie of 

 waste disposal. Variation in treatment process was a companion to change in 

 river-flow level. Treatment plants involve sizeable capital outlay and are fixed, 

 once built. Shifting between processes and for some firms, entering and leaving 

 production cannot easily be done with each change in river-flow level. In plan- 

 ning, some flow level between the median and low level could serve as a guideline 

 in determining optimal resource allocation under variable flow conditions. 



The variation in river flow also leads to differences in cost allocation. Optimal 

 activity on a basin-wide basis may not be optimal for some specific sector. This 

 fact provides economic foundation to conflicts in the choice of activity in water- 

 resource planning among sectors. The conflicts may hinder coordinated effort in 

 reaching quality standards and economic development. However, features in 

 this analysis would encourage cooperative effort. First, the optimal treatment 

 process in industry and in community water purification and waste-water treat- 

 ment were the same or very similar. Second, there are economies of size in 

 waste-water treatment plants and in cooperative efforts between communities 

 and industry, usually resulting in reduction of cost to all concerned. Third, 

 benefits from coordinated effort may be reciprocal in that the beneflts may 



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