be an upgrading in the quality of the fishing days as measured by the species 

 sought. Higher quality days are valued more than lower quality days. This 

 method does not provide an estimate of the benefit due to added enjoyment of 

 each fishing day attributable to higher water quality per se (e.g., to greater 

 clarity or better smell). 



The details of the economic justification of our central hypothesis are 

 rather arcane and unlikely to interest any but other economists. Even more 

 arcane is the justification for using the change in participation (days) times 

 the average of fishermen's prepollution-control values of their fishing days 

 (distinguished by species sought) as the measure of program benefits. And our 

 interests in this paper lie elsewhere in any case. Therefore, let us concentrate 

 on the knowledge necessary to use the method, accepting that it is defensible. 

 (The skeptical reader is invited to read Vaughn and Russell 1981 before making 

 a decision on this point.) 



The linkages we should be able to understand and model (whether formally 

 or informally, in order to apply the method outlined above for obtaining national 

 benefit estimates) may be summarized as follows: 



- We should be able to predict how policy implementation will affect 

 pollution discharges by location, quantity, and pollutant type across 

 the entire nation. 



- We should be able to predict how the pre- and post-policy discharge 

 levels affect ambient water quality (or how ambient quality changes as 

 discharges change) in terms not only of such familiar indicators as 

 dissolved oxygen (DO), but in terms of supportable fish population 

 types (or other measures relevant to participation decisions). 



- We should be able to predict how increases in total amounts of water 

 supporting recreational fishing and shifts in the composition of that 

 water toward more highly valued fish species affect numbers of anglers 

 and the amount of time they spend fishing. 



- We should be able to put values on fishing activity of various kinds 

 (that is, for practical purposes, on days spent fishing for various 

 species). 



i 

 This list suggests some of the formidable difficulties in the way of producing 

 national benefit estimates for even this one subcategory. Just the first 

 linkage, from law to changes in discharges, while not necessarily involving 

 subtle economic or biological questions, does require massive amounts of 

 information for every affected water body in the country. The last two linkages 

 are the explicitly economic matters, and we shall ignore them in this paper. 

 Instead, we shall concentrate on the second linkage, that from changes in 

 pollution discharges to changes in one or another measure of water (or ecosystem) 

 quality directly relevant to the sport fishing participation decisions of 

 individuals. 



Pollution Discharges and Water Quality Prediction in the Freshwater Study 



We had available at Resources for the Future (RFF) a very large and complete 



39 



