Low-Flow, High Stakes: CAP Fellows Review Climate-Driven Flows and Management Across the U.S.
In a new publication, the 2022-2024 Climate Adaptation Postdoctoral Fellows cohort explores how climate-driven low-flows in rivers alter water quality, how those water quality changes influence ecosystem health, and how instream flow management has been used across the U.S. to address these challenges.
Across the country, rivers and streams are experiencing declining water quality as low-flow extremes become more common. These low-flow events, or periods when rivers have reduced water levels, are strongly influenced by increasing temperatures, rainfall extremes, and a growing demand for fresh water.
Low-flows were the focus of a national synthesis project led by the CASC Climate Adaptation Postdoctoral (CAP) Fellows ‘Future of Aquatic Flows’ cohort. The team, comprised of post-docs located in each CASC region, conducted a review of the current literature and expert knowledge to better understand the influence of low-flows on water quality and aquatic ecosystems across the U.S., and its implications for future management.
Their research found that although the drivers of low-flows vary across the country, certain water quality patterns are consistent. For example, low-flows are frequently connected to higher stream temperatures, particularly in urbanized areas and the western U.S. When river temperature is warmer, dissolved oxygen levels drop and salinity increases, creating challenges for ecological, municipal, and agricultural water usage. Degraded water quality has detrimental impacts on aquatic ecosystems, including disrupting food webs, reducing habitat connectivity, and increasing macroinvertebrate mortality.
While several river management frameworks have been developed to address these challenges, they differ in their geographic scale and in how they integrate water quality measures. Since ecological impacts vary by river and location, the team suggests that local case studies could be used to highlight successful management approaches and help regions across the U.S. collaborate on similar low-flow issues. To better inform the long-term resilience of river ecosystems, they recommend that scientists seeking to understand river management priorities collaborate more closely with managers to develop and use frameworks that emphasize water quality measures.
As changes in temperature and precipitation patterns exacerbate challenges for managers and ecosystem health, incorporating water quality into place-based management approaches can help keep river flows in balance.
This national synthesis was completed as part of the Future of Aquatic Flows cohort (2022-24) of the Climate Adaptation Postdoctoral (CAP) Fellows Program. Hosted by the CASCs, the CAP Fellows Program brings together postdoctoral scholars from around the country to conduct independent and collaborative research directly applicable to regional management priorities.