National framework for ranking lakes by potential for anthropogenic hydro-alteration
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Lake hydrology faces multiple stressors from human activity. Land use (e.g., irrigated agriculture) and dams can alter lake inflows and outflows beyond natural ranges and changing climate conditions may exacerbate these disturbances. Broad-scale hydrologic disturbance measures are needed to assess human impacts on lake hydrology at regional and national extents. We developed a framework to rank lakes by the potential for anthropogenic alteration of lake hydrology (HydrAP) caused by dams and land use activities using national-scale datasets. We ranked lakes in the US EPA National Lakes Assessment (NLA) on a scale from zero to seven, spanning lakes with no apparent human hydrologic disturbances to lakes with large dams and/or intensive land use with potential to alter water levels. We inferred population HydrAP distributions in the conterminous US (CONUS) using the NLA probabilistic weights. About half of CONUS lakes were estimated to have moderate to high hydro-alteration potential (HydrAP ranks 3-7) and the other half had no to minimal hydro-alteration potential (HydrAP ranks 0-2). Water residence time (τ) and lake water-level change were associated with HydrAP ranks and support the framework’s ability to identify human infrastructure and activities that can alter lake hydrology. Lake τ were shorter in high HydrAP-ranked lakes. However, water-level change and HydrAP relationships varied by ecoregion and likely reflect different regional water management strategies that can promote or suppress large water-level fluctuations. The HydrAP framework is a robust tool to estimate human hydrologic disturbances and offers promise to support large-scale lake hydrologic assessments.