APPENDIX G 

 Conceptual Basis for Compensation of Unmitigated Impact 



Strategies of mitigation and compensation may be considered conceptually 

 by examination of Figure 18. In this figure, carrying capacity (K) is shown 

 as a function of time (with seasonal, successional , and other variations smoothed 

 out) under various management strategies. Carrying capacity with management is 

 shown by dashed lines; that which would be the case if the management technique 

 were not applied is shown by solid lines. Carrying capacity may be considered 

 proportional to the "habitat units" of the U.S. Fish and Wildlife Service Hab- 

 itat Evaluation Procedures (Schamberger and Farmer 1978); thus, similar figures 

 may be constructed based on actual field data. 



In Figure 18-1, a solid curve is shown which represents, as a function 

 of time f(t), the change in K resulting form an unmitigated, short-term impact. 

 The dashed curve in this same figure shows how mitigation might serve to lessen 

 the reduction in K over time according to a different function of time, m(t). 

 The benefits B,^ to the population which could be obtained by mitigation, repre- 

 sented as the shaded area in Figure 18-1, would thus be 



t 



m(t) - f(t) dt. 



If the costs of mitigation are Cm, the benefit per unit cost (expressed as 

 habitat unit days or a similar measure) is simply Bm/Cm = E^, which is a 

 measure of the cost-effectiveness of mitigation. Note that, in this figure, 

 some losses accrue over time even with mitigation. 



Two strategies for compensating this unmitigated impact are described 

 below. If justified on the basis of cost-effectiveness, such strategies may 

 even be considered as substitutes for mitigation in certain cases. Figures 

 18-11 and 18-III show these two alternatives. In both cases, the impact curve 

 f(t) is the same as in figure 18-1, but the impacts are not mitigated and 

 simply accepted as they are. The impact-related losses L to the resource are 

 thus equal to the difference between the situation if the impact did not occur 

 (represented by a dotted line) and the function h'(t) and f(t), or 



L = 



rm(t) - f(t)1 dt. 



Compensation by Enhancement 



In figure 18-11, the carrying capacity of enhancement land is represented 

 by the solid line r(t). Long-term enhancement of this area may increase the 



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