Watershed implementation plans developed by the U.S. Environmental Protection Agency and its state and local partners to protect water quality may be vulnerable to future challenges such as climate change, new research suggests.

The RAND Corporation looked at two pilot case studies — one on the Patuxent River in Maryland and one on the North Farm Creek tributary of the Illinois River — to explore how analytic robust decision making (RDM) methods can help ensure these plans are more robust to such uncertainty.

According to the researchers, RDM can help planners identify future vulnerabilities in total maximum daily load (TMDL) implementation planning.

In both case studies, the proposed plans meet their water quality goals under current assumptions, but not in many other plausible climate and other scenarios. For example, an increase in the amount of paved or impervious area cover due to future population growth could lead to standards being missed.

The study found, however, that modified plans and adaptive management approaches can often reduce these vulnerabilities.

In order to improve and maintain high water quality standards in changing, often difficult-to-predict conditions, RAND recommends that the Environmental Protection Agency and its partners employ iterative risk management processes and adopt water quality implementation plans that are robust and flexible.

The study, Managing Water Quality in the Face of Uncertainty: A Robust Decision Making Demonstration for EPA’s National Water Program, is available at http://www.rand.org/pubs/research_reports/RR720.html.