Affiliation:
1. Center for Applied Aquatic Ecology, North Carolina State University, Raleigh, NC 27695, USA
Abstract
Reservoirs are increasingly valuable worldwide as potable source waters, yet in many geographic regions, their limnology and trophic status are poorly known. We characterized 14 drinking water reservoirs and their watersheds across the warming temperate/subtropical southeastern USA. Selected reservoirs had at least three years of accessible summer water quality data during 2010–2020, including Secchi depth, nutrients, and algal biomass as chlorophyll a, and depth profiles for temperature and dissolved oxygen. Most watersheds, including lands within a 10-km radius of the reservoirs, had sustained substantial urbanization and/or intensive industrialized animal production, in some cases including the discharge of partially treated human sewage or livestock slaughterhouse wastes near or into the reservoirs. Five reservoirs were assessed as mesotrophic; the others were eutrophic. Most were stratified, but ephemeral near-surface thermoclines were common, and many were too shallow (median depth 5.0 m) to maintain uniform temperatures in the relatively warm hypolimnia. Bottom-water hypoxia/anoxia occurred throughout the summers but, surprisingly, in 8 of 14 reservoirs hypoxia commonly extended to surface waters. In the Southeast as in many regions, drinking water reservoirs are poorly protected and degrading as livestock production and/or urban development increasingly characterize their watersheds. The eutrophication trajectory of these valuable resources should be used as an indicator of ecosystem health and water quality in developing more protective management and policy actions.
Funder
City of Raleigh Public Utilities
National Institute of Food and Agriculture
Subject
Water Science and Technology,Aquatic Science,Geography, Planning and Development,Biochemistry
Reference260 articles.
1. Estimating watershed degradation over the last century and its impact on water-treatment costs for the world’s large cities;McDonald;Proc. Natl. Acad. Sci. USA,2016
2. Water availability and vulnerability of 225 large cities in the United States;Padowski;Water Resour. Res.,2012
3. Oliver, S., Corburn, J., and Ribeiro, H. (2019). Challenges regarding water quality of eutrophic reservoirs in urban landscapes: A mapping literature review. Int. J. Environ. Res. Public Health, 16.
4. Ingram, K.T., Dow, K., Carter, L., and Anderson, J. (2013). Climate of the Southeast United States, Island Press. NCA Regional Input Reports.
5. Wetzel, R.G. (2001). Limnology: Lake and River Ecosystems, Academic Press. [3rd ed.].