Identification and characterization of urban lakes across the continental United States

Abstract

Abstract Costadone L, Sytsma MD. 2022. Identification and characterization of urban lakes across the continental United States. Lake Reserv Manage. 38:126–138. Urban lakes contribute to the quality of life and sustainability of urban areas by providing a variety of ecosystems services. We defined and identified urban lakes across the continental United States; provided a comprehensive assessment of water quality, management activities, and ecosystem services; and determined how these systems compare to non-urban lakes. Lakes and reservoirs were identified as “urban” if they were completely within areas with at least 50,000 people, and in a subwatershed with a population density of at least 1000 people per square mile (386 people per square kilometer) and more than 10% of impervious cover. We identified 1950 urban lakes and reservoirs that were compared to a population of 2066 non-urban lakes identified from the National Lake Assessments. Urban lakes were smaller, shallower, and in a more disturbed condition than non-urban lakes due to high chlorophyll a (Chl-a) concentration, based on reference conditions for a given ecoregion. Analysis of the phosphorus–chlorophyll relationship at the ecoregional level revealed that there was a significant difference in the relationship between Chl-a and total phosphorus (TP) between urban and non-urban lakes in every ecoregion except in the Northern Appalachian, Xeric, and Upper Midwest ecoregions. A significantly higher proportion of urban lakes were eutrophic in all ecoregions, except in the Coastal Plains, Southern Plains, and Temperate Plains ecoregions. Urban lakes had different causes of water quality impairment compare to non-urban lakes. Given the differing ecological functioning, causes of impairment, and services provided, more targeted management may therefore be necessary to address the particular challenges urban lakes are facing.