Exploring flow guidelines for a free-flowing river in a human dominated landscape: The Flint River Georgia

Background/Question/Methods:  Recent droughts have elevated concerns about water security, i.e., the ability to provide for public supply and support in stream requirements for healthy biota and associated ecosystem services. These concerns are amplified in Georgia and the southeastern US by projections of increasing population, increasing temperatures, increasing agricultural production, and uncertain precipitation. Management approaches focused on anticipating and guiding ecological responses are urgently needed to ensure the full value of aquatic ecosystem services for future generations. This acknowledges that change is inevitable and sometimes irreversible, and that maintenance of ecosystem services depends in part on novel ecosystems, i.e., species combinations with no analog in the past. Potential ecosystem responses should be evaluated at landscape or regional scales using risk-based approaches to incorporate uncertainty into assessment efforts with subsequent goals for management based on Achievable Future Conditions (AFC). AFCs encompass mitigative and adaptative options for scenarios of projected biophysical, social-economic, and policy conditions which distribute risk and provide diversity of response to uncertainty. 

Results/Conclusions:  The Flint River in Georgia is used as a case study to demonstrate this conceptual framework. Substantial declines in daily flows during April through October are apparent in the flow record for the past 30+ years. The Flint River appears at risk for moderate to severe ecological degradation due to flow alteration. Biota and ecological processes depending upon historic summer flows appear to be at greatest risk. While specific biological responses are largely undocumented, enough is known to suggest that several important faunal groups including freshwater fishes, mussels, and crayfishes will, or are being, adversely affected. Sufficient technical information also exists to guide initial management responses and a stream-flow monitoring network is in place to provide feedback. The challenge lies with engaging diverse social and economic interests in a formal process leading to provision of stream flows that sustain ecological structure and function. Actions might include more rapid responses to existing drought early warning systems (better triggers) and enhanced water conservation efforts, particularly in the upper watershed.  Actions may also include coordinated pulsed or incremental releases from upstream tributary reservoirs to supplement stressed mainstem baseflows.