Applying Results Findings: the Recovery Potential Project

Abstract

The growing body of evidence and results from numerous restoration projects, TMDLs, and other efforts demonstrate that the success of efforts to restore impaired waters is closely linked with watershed and waterbody traits that influence the potential of the waterbody to recover its functionality. Restoration success is not exclusively determined by the success or failure of the externally applied restoration techniques. Specific attributes of the waterbody itself and its watershed collectively indicate its recovery potential, and can be represented by metrics of three primary types: measures of ecological capacity to reestablish natural processes, measures of current and projected stressor exposure, and measures of social context. These metrics can be identified and evaluated at a screening level to compare recovery prospects across multiple sites, using landscape modeling methods as a tool for broad-area planning and priority-setting for impaired waters restoration. In the Clean Water Act’s TMDL program and Section 319 nonpoint source grants program as well as in state restoration initiatives, states face challenging decisions on which sites to address in what order, with what fraction of limited restoration resources. Our project’s goal was to develop and demonstrate statewide-scale analytical tools that could help states carry out these tasks with more systematic and science-based consideration of recovery potential as a primary driver. An extensive search of the restoration literature was used to initially identify recovery-potential-related traits from empirical studies and syntheses, and then evaluate the ability to translate each of these traits into spatial metrics with specific, GIS-based measurement protocols. This effort resulted in the development of over 80 recovery potential indicators across the aforementioned categories of ecological capacity, stressor exposure, and social context. Using as a hypothetical test bed the 2002 State of Illinois’ 303(d) list for approximately 725 impaired waters, EPA impaired waters databases, and numerous supporting GIS datasets, we developed several approaches for prioritizing impaired waterbodies based on recovery potential. We focused on developing suites of prioritization options to demonstrate recovery potential as a flexible statewide screening tool, and because the differing context of each impairment suggests that a single prioritization scheme would not likely be suitable for all impaired waters or the priority decisions of all states. In the analyses presented here, we compare rank orders (highest rank = most recoverable) of selected measures of ecological capacity and social context to the nominal priority ranks of low, medium and high that accompanied the 2002 Illinois 303(d) list. The simple, single-indicator comparisons demonstrate site-to-site variability in factors that should influence likelihood of recovery. We close with a cluster analysis of recovery potential metrics, again comparing the cluster groups to the nominal priority rankings of low, medium, and high. The results of the cluster analysis suggest that there is a geography to recovery potential. We discuss how the geographic pattern in the cluster groups could be exploited as a TMDL and restoration prioritization tool. Wickham, J.D. and D.J. Norton. 2007. Applying results findings: the recovery potential project. Proceedings: Water Environment Federation TMDL 2007 Conference, Bellevue, WA, pp. 492-506.