Assessing Stormwater Control Measure Inventories from 23 Cities in the United States
Despite over $5 billion dollars in expenditures, nonpoint source pollution from urban watersheds is still a significant cause of impaired waters in the United States. Urban stormwater management has rapidly evolved over recent decades with decision-making made on a local or city-scale. To address the need for a better understanding of how stormwater management has been implemented in different cities, we used stormwater control measure network data from 23 United States cities and assessed what physical, climatic, socioeconomic, and/or regulatory explanatory variables, if any, are related to stormwater control measure assemblages at the municipal scale.
Map of 23 U.S. study cities. Legend defines Köppen climate zones and how many cities fall within each zone. MS4P-CSO specifies if each city is a MS4 Phase I (I) or Phase II (II) city and if the city has a combined sewer present (Y) or not (N).
Proportion of stormwater control measure types as defined by the fine classification system established by the Water Environment Federation and American Society of Civil Engineers ordered from least to most diverse from left to right based on diversity index scores. Stormwater control measures are color coded: Blue-Purple: Basins, Gray: Swales and Strips, Orange-Brown: Filters, and Light Green-Dark Green: Infiltrators.
These analyses showed that for the cities assessed, physical explanatory variables (e.g., impervious percentage and depth to water table) explained the greatest portion of variability in stormwater control measure assemblages. Additionally, it was found that cities with combined sewers favored filters, swales and strips, and infiltrators over basins, and cities that are under consent decrees with the EPA tended to include filters more frequently in their stormwater control measure inventories. Future work can build on the stormwater control measure assemblages used in this study and their explanatory variables to better understand the differences and drivers of differences in stormwater effectiveness across cities.
For more information: Choat et al 2023 Environ. Res.: Infrastruct. Sustain. https://doi.org/10.1088/2634-4505/acc759