across a wide geographic area. The two alternatives might be equal in one unit of measurement, but may not be equal in terms of production costs and preferences to the anglers.
There are instances where cost-effectiveness analysis of supplying some desired number of HEP units is appropriate. A common instance is where protection of an endangered species is called for and the particular HEP model is calibrated to that species. In this instance, the Corps is helping to fulfill a legislative mandate and there is no need to conduct a benefit-cost analysis, only to accomplish the mandate at the lowest cost, subject perhaps to a spending constraint.
The interesting and challenging task for the Corps is to link outputs of ecological models, in whatever units are appropriate, with economic benefits. In doing so, the Corps should be careful not to confuse HEP unit maximization with actual restoration of the original ecosystem.
Conventional Corps planning studies discount all future flows of monetized benefits to present values using a single interest rate mandated by the Office of Management and Budget. Several issues arise regarding the choice of a particular discount rate and how it is chosen. One of these issues is the following: What is an appropriate choice when a current change in an environmental amenity is being traded off against a distant future change in that same amenity? Other federal agencies, such as the EPA and NOAA, are starting to consider this issue, as should the Corps. Coordination of a consistent federal policy on this issue would be desirable.