Using decision analysis to choose phosphorus targets for Lake Erie

Lake Erie water quality has improved dramatically since the degraded condit ions of the 1960s. Additional gains could be made, but at the expense of fu rther investment and reductions in fishery productivity. In facing such cro ss jurisdictional issues, natural resource managers in Canada and the Unite d States must grapple with conflicting objectives and important uncertainti es, while considering the priorities of the public that live in the basin. The techniques and tools of decision analysis have been used successfully t o deal with such decision problems in a range of environmental settings, bu t infrequently in the Great Lakes. The objective of this paper is to illust rate how such techniques might be brought to bear on an important, real dec ision currently facing Lake Erie resource managers and stakeholders: the ch oice of new phosphorus loading targets for the lake. The heart of our appro ach is a systematic elicitation of stakeholder preferences and an investiga tion of the degree to which different phosphorus-loading policies might sat isfy ecosystem objectives. Results show that there are potential benefits t o changing the historical policy of reducing phosphorus loads in Lake Erie.