A Multi-objective, Return on Investment Analysis for Freshwater Conservation Planning

Efforts toward systematic conservation planning for freshwaters have progressed less than similar efforts in terrestrial and marine environments. Although there are important differences, many of the tools that have been used in terrestrial and marine systems can also be used for freshwater conservation planning. In this paper, we used return on investment (ROI) analysis to identify optimal riparian land conservation portfolios under different objectives. Our overarching research question is: how do different strategies for evaluating ROI objectives influence the resulting conservation portfolio and the outcome of interest, lake water quality? We examined agricultural riparian land investments to improve water quality in 55 inland lakes in southwestern Michigan. We simulated investments and compared the ROIs for the following strategies: (1) economic; (2) ecological; and (3) environmental policy. Furthermore, as a reference point, we also compared the resulting three conservation portfolios to that derived by simulating riparian land enrollment under the Conservation Reserve Program. We found that (1) investments in freshwater resources through the conservation of riparian land were more effective than the conservation of randomly selected parcels of similar land area in the catchment; (2) the costs and benefits of riparian land conservation varied considerably among lakes; (3) the choice of investment objectives, and therefore ROI strategies, resulted in very different conservation portfolios; (4) the simulated enrollment process of the Conservation Reserve Program fared poorly in terms of improving lake water quality as compared to the three strategies.