would be least harmful to the environment? How can a designer know whether a compound made of material x would be better or worse for the environment than a compound made of material y? In some cases, the answers to these questions are straightforward, but in many cases they are not.

Ideally, a change in environmental performance could be measured in units of ecosystem condition. For example, computer design might be assessed a priori in terms of its expected per-unit impact on, for example, the water quality in streams that receive effluent from the computer factory. Recent efforts have attempted to extend life-cycle assessment procedures toward this goal (Steen and Ryding, 1992), but those efforts have been criticized because of the difficulty of ranking the environmental significance of different types of impacts. In other words, there is inadequate information on how different impacts affect ecosystems. As a result, critics are unconvinced that improvements in environmental performance measures will correlate with improvements in ecosystem conditions (Field and Ehrenfeld, this volume). Absent any correlation, efforts to improve environmental performance could be ineffective or even possibly counterproductive.

In other cases, there may be insufficient information to confirm that adherence to environmental performance standards does safeguard impacted ecosystems. For example, federal regulations require the use of bioassays to measure the toxicity of effluents released directly into waterways (Goulden, this volume). The presumption is that if the effluent bioassay results meet the environmental performance standard, then the ecosystem will not be harmed. Goulden argues that this is not a safe assumption. This appears to be another case of insufficient collaboration and cooperation between managers of environmental performance and managers of ecosystems. Hart (1994, p. 111) notes that the Intergovernmental Task Force on Monitoring Water Quality determined that ". . . for every dollar invested in programs and infrastructure designed to reduce water pollution, less than two-tenths of one cent (or 0.2 percent) was spent to monitor the effectiveness of such abatement programs!" Field and Ehrenfeld and Goulden essentially argue that one can not assume that an improvement in environmental performance, as measured by life-cycle assessment or effluent bioassays, leads to even an incremental improvement in ecosystem condition. Clearly, there is ample room for better coordination and collaboration between students of environmental performance and students of ecosystem condition.

Although it is probably too much to expect a comprehensive ability to predict how each particular human activity affects ecosystems, existing evidence suggests that collaboration between ecologists and engineers can be a powerful means of simultaneously achieving engineering objectives and environmental goals. Shen (1996) and Lindstedt-Siva et al. (1996) describe relevant examples from the fields of oil exploration and water management. In both cases, explicit environmental objectives served as engineering design constraints. Environmental scientists identified precise design criteria that engineers then used. The

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