no method is foolproof, this value can be captured through questionnaires, surveys, and votes (see also Schelling, 1968). These methods today are used around the world (Hanemann, 1994) and are continually being refined. Of recent studies that have attracted attention, a group effort in the late 1990s that attempted to value all of the planet 's ecosystem services and natural capital stood out (Costanza et al., 1997). This 1997 paper was quick to point out that, due to the study 's complexity and ambition, that it was merely a first approximation of these values. In the field of water resources planning, there is a large and growing literature on valuation of the services of riverine and aquatic ecosystems (e.g., Bishop et al., 1987; Douglas and Taylor, 1998; Loomis, 1998).
These valuation methods, while essential in a complete examination of costs and benefits of project alternatives, cannot be usefully applied in the absence of well-defined descriptions of the range of environmental impacts that are associated with project alternatives. Moreover, these valuation methods will not be capable of quantifying (in dollars) all the environmental costs associated with alternatives. They are best suited for quantifying costs associated with environmental impacts that relate to human use of affected resources (such as boating and sport fishing) and impacts that can adequately be described to the public in the context of survey instruments of the type used in contingent valuation.
Recreation. A 1995 study sponsored by the Corps documents over 12 million visitor days annually, with associated annual economic impacts of $1.2 billion in recreation activities directly linked to uses of the UMR–IWW system (Carlson et al., 1995). Although they are not addressed in the feasibility study, recreation user benefits (consumer surplus to recreational users) are generated by these user-days (as are the economic impacts on businesses cited above). Direct benefits to recreational users are part of NED and should be considered in project evaluation.
Prior research suggests that river recreation is negatively affected by increased commercial barge traffic (Becker, 1981; Graman et al., 1984). In particular, recreational boaters respond to increased traffic by foregoing recreational boating and by relocating their activities to other sites that are not affected by higher traffic (with higher travel costs incurred and lower consumer surplus generated). This type of effect on recreation is consistent with studies of other forms of recreation that indicate a negative relationship between increased congestion and user benefits. Analogies can be found in the literature which documents negative impacts of increasing numbers of users at parks, fishing sites, reservoirs and hiking trails on recreation user benefits (Loomis and Walsh, 1997; pp. 104–109). The recreation economics literature clearly demonstrates that benefits per user-day fall notably as the number of encounters with other parties rises. This phenomenon should be incorporated in the analysis of project alternatives, which should explicitly model and quantify the relationships between recreation use benefits for boating and fishing and changes in commercial barge traffic levels.
River-related recreation benefits in the study area represent significant economic benefits provided by the Upper Mississippi River and are likely to be affected by many of the navigation project alternatives. The Corps should commence with a detailed analysis of impacts on recreation use benefits, going beyond the consideration of only boater safety and lock delays.