An assessment of the condition of flowing waters in predominantly urban areas of the conterminous U.S. and its relationship to measures of environmental justice

Abstract

Urbanization often leads to environmental degradation and there is a growing concern that these impacts are inequitably distributed. We assessed the condition of urban flowing waters across the conterminous US using data from EPA’s National Rivers and Streams Assessment and tested whether degradation was related to metrics of environmental justice (EJ). We found that urban flowing waters are more degraded than their non-urban counterparts. Indeed, the proportion of the length of the nation’s urban flowing waters in poor condition, based on common environmental quality indicators, was often nearly twice as high as the proportion for the nation’s flowing waters as a whole. The majority of urban waters were in poor ecological condition for water quality integrity, nutrient concentrations, and riparian disturbance although, most were in good ecological condition for riparian vegetation, instream cover, bed sediment, enterococci, and dissolved oxygen. For biological indicators, urban flowing water was mostly in poor condition for both fish (52% of total length) and macroinvertebrate biotic integrity (80% of total length). Despite widespread degradation, we did not find that flowing water degradation was strongly related to the two EJ measures we analyzed (% low income and % minority). The highest correlations we observed (|r|=0.3) were between fish biotic integrity and % low income, and between riparian disturbance and % low income. To our knowledge, this is the first study to assess the pervasiveness of urban flowing water degradation and its relationship to EJ on a national scale. While this study did not uncover a compelling association between the studied environmental parameters and income and minority status in the surrounding human population, more research is needed to assess access to healthy rivers and streams for all communities.