August 2023: Mike Piehler

Director of the UNC-Chapel Hill Institute for the Environment
Professor, UNC-Chapel Hill Department of Earth, Marine and Environmental Sciences

Falls Lake Study Builds our Understanding of Southeastern Reservoirs

The Falls Lake Study is a collection of research projects supported by the Collaboratory with funding from the North Carolina General Assembly. The legislature directed UNC-Chapel Hill to oversee a study and analysis of nutrient management strategies and synthesis of existing water quality data in the context of Falls Lake.

Several distinct research teams are evaluating a number of factors related to the water quality of Falls Lake, including flows in and out of the lake, the potential for development of toxic algae, review of existing modeling efforts, mitigation strategies and financial resources available for those strategies. Dr. Mike Piehler has served as the faculty lead of the study.

Why did the NC legislature commission the Falls Lake Study?

Falls Lake is a reservoir built when the Neuse River was dammed at a time when there was less population in the watershed. The Falls Lake Study was commissioned by the NC legislature they had a strong interest in understanding how the water quality rules aligned with the reality of the conditions in the reservoir and the surrounding watershed. They wanted an interpretation of the existing data, an assessment of what new data might be needed to answer questions to meet goals and understand costs.

How is the study’s research advancing our knowledge of Falls Lake?

At Falls Lake we were fortunate that the Upper Neuse River Basin Association had been collecting fantastic data for many years before we began our work. We’ve been able to collect a huge amount of new data on the biological, chemical and physical features of the reservoir and interpret the relevance in the context of the activities and needs of people. A couple of highlights included and improved understanding of the physical transport of water. That’s important because there were physical dynamics that would not have been anticipated and play a large role in shaping water quality in the reservoir. Additionally, UNC-Chapel Hill Environmental Finance Center has played a big part in understanding the nature of the opportunities for funding for these projects and new frameworks to allow distribution of the cost intervention. They have developed a ‘revenue shed’ model for the reservoir that equitably distributes the cost of retaining the quality of the system.

Why is it important we better understand reservoirs in the Southeast?

We’re going to need all the water we can get! There are lots of indications that we’re coming up to a time where we’re going to be challenged by both flooding of water where we don’t want it when we don’t want it, and water scarcity. Reservoirs are going to be really important for storing water as a water resource. The southeastern US continues to experience explosive population growth. The natural conditions of Southeast reservoirs are really conducive to the excessive growth of algae. A lot of information was brought forward about how distinctive southeastern reservoirs are in general. The more we know about them, the better we’re going to be at managing them.

What are some of the policy implications of the Falls Lake Study’s findings?

I think the study’s findings added fuel to the policy conversations around what our expectations should be from proposed management interventions, and what to expect for the return of investment. The study has helped refine our understanding of the controls on the function of the reservoir and how best to try to maintain and improve water quality from a policy perspective. For me, as a scientist who’s interested in how science helps solve problems, it’s been great to further explore the physical processes, nutrient cycling, and food web analysis in consideration of what are the right indicators of successful management are. Our findings supported the importance of looking at what the targets are, whether they’re the right targets, and whether they’re the right magnitude for that target.