Green infrastructure and green stormwater infrastructure terminology

Over the past decades, several terms have been used to describe stormwater practices and management. This is particularly true of practices designed to mimic natural processes (e.g. infiltration, evapotranspiration, etc.). The terminology has therefore become somewhat confusing. Below is the terminology and definitions we use in this manual. Links are provided to articles discussing this terminology.

• Best management practice: One of many different structural or non–structural methods used to treat runoff
• Better site design: Better site design includes a series of techniques that reduce impervious cover, conserve natural areas, and use pervious areas to more effectively treat stormwater runoff (Center for Watershed Protection, 1998a) and promote the treatment train approach to runoff management.
• Blue-Green Infrastructure (BGI): an approach to urban flood resilience, recognized globally and in international literature, that capitalizes on the benefits of working with urban green-spaces and naturalized water-flows.
• Gray infrastructure: Gray stormwater infrastructure is designed to move urban stormwater away from the built environment and includes curbs, gutters, drains, piping, and collection systems. Generally, traditional gray infrastructure collects and conveys stormwater from impervious surfaces, such as roadways, parking lots and rooftops, into a series of piping that ultimately discharges untreated stormwater into a local water body.
• Green infrastructure: Green Infrastructure refers to ecological systems, both natural and engineered, that act as living infrastructure. Green Infrastructure elements are planned and managed primarily for stormwater control, but also exhibit social, economic and environmental benefits (Syracuse University).
• Green stormwater infrastructure: Green stormwater infrastructure (GSI) describes stormwater practices that use natural systems (or engineered systems that mimic or use natural processes) to capture, clean, and infiltrate stormwater; shade and cool surfaces and buildings; reduce flooding, create wildlife habitat; and provide other services that improve environmental quality and communities’ quality of life. Examples include green roofs, bioretention, tree trenches, and vegetated swales (Tucson).
• Low impact development: Systems and practices that use or mimic natural processes that result in the infiltration, evapotranspiration or use of stormwater in order to protect water quality and associated aquatic habitat (US EPA).
• Nature-based solution: Actions designed to protect, sustainably manage, and restore natural and modified ecosystems that address societal challenges effectively and adaptively, simultaneously providing human well-being and biodiversity benefits (International Union for Conservation of Nature).
• Stormwater control measure: A technique, measure, or structural control that is used for a given set of conditions to manage the quantity and improve the quality of stormwater runoff in the most cost-effective manner (US EPA).