360 
pollution discharges where there are no water quality problems are in- 
significant and 2) that the benefits of reducing pollution discharges 
even where there are water quality problems are insignificant unless 
the exceedance is eliminated. 
Under these assumptions, the most cost-effective option would be the option with 
the lowest cost per exceedance eliminated. Thus, those options that require 
uniform action irrespective of local conditions (untargeted options) are likely 
to be less cost-effective than those options that take local conditions into 
account (targeted options). This conclusion is most apparant for Option la 
(the existing program) which requires about one half of the POTWs to implement 
categorical standards even though they have no exceedances; the result is that 
it costs twice as mich as Option lb (the existing program with waivers) to 
have the same effect on exceedances. The cost per exceedance eliminated for 
all of the options based on categorical standards is shown below. 
COST PER EXCEEDANCE ELIMINATED FOR CATEGORICAL STANDARDS 
(Millions of Dollars) 
ALL INDUSTRIES METAL FINISHING ONLY 
UNT ARGET ED 30 - 31 20.5 = 21.5 
TARGETED (WAIVERS) 13.8 = 14.2 9.4 = 9.9 
On this basis, Option 2a, categorical standards for metal finishing only with 
water quality waivers appears to be most cost-effective of the options that 
rely on categorical standards. 
va 
It fs not possible in this report to analyze the cost-per-exceedance 
of the water quality-based options because it is not known how many exceedances 
would be eliminated or what the total cost would be. Presumably, however, 
the costs would be in line with the benefits because the States would always 
have the option of downgrading the designated stream use if the costs outweighed 
the benefits of attaining water quality standards. 
