Concentrating development is an important strategy for improving water resource management. Locating population and jobs in existing urban and suburban centers can protect fragile headwaters, aquifers, streams and wetlands. Intensive land uses allow wastewater and water supply systems to operate more efficiently by enabling cost effective collection, distribution and reuse.
But managing the rainwater that falls or flows within urban areas poses challenges. The purpose of this document is to help planners working in urban, suburban and rural areas achieve both land use and water management goals. Impervious pavement and buildings disrupt the infiltration of water into the ground, depriving plants and aquifers of moisture. Instead, urban rainfall quickly flows over parking lots, rooftops, streets and sidewalks, picking up pollutants and sediment on the way downhill. This concentrates stormwater both time and space, making urban areas prone to flooding and downstream watersheds subject to erosion and pollution. For low-lying neighborhoods, this accumulated water can inundate homes, businesses and critical infrastructure, placing people at risk and costing millions of dollars each year in damage and lost business. In cities with combined sewer systems, even moderate rainfall can overwhelm treatment plants and trigger overflows that dump untreated sewage into watercourses. Moreover, rainwater is an important resource that can be productively used for a variety of purposes. Limited access to freshwater and increased energy costs of pumping and cleaning water, makes this important even in water-rich regions of the country. Our changing climate will exacerbate these problems. Scientists anticipate more frequent high-intensity storms, challenging the design of water systems engineered for gentler weather patterns.
There will be greater incidences of drought, making the reuse and storage of stormwater a necessity. Single purpose, end-of-the-pipe solutions that rely heavily on pipes, storage tanks and other physical structures—collectively referred to as gray infrastructure—are methods traditional of addressing water quality and quantity concerns. But these capital-intensive solutions are becoming increasingly cost-prohibitive, difficult to site and inadequate for meeting today’s water challenges. Green infrastructure systems – which help manage stormwater and wastewater through conservation of forests, fields and wetlands as well as engineered processes that draw inspiration from nature – offer great promise for improving water resource management in urban areas. Green infrastructure systems encourage infiltration and reduce peak flows to streets and storm sewers. They have been used to successfully address a variety of critical water management goals, including protecting clean drinking water, providing water for irrigation and protecting people and property from flooding. Green infrastructure has additional benefits. The plants and soils, green city streets and sidewalks, improve air quality, reduce energy demand and enhance wildlife habitat and recreational opportunities. Protecting and enhancing stream corridors and other green spaces can be an important component of an overall design strategy for communities, helping create a place that people want to live, work and play.
These innovative solutions have gained currency in the Environmental Protection Agency and some state and local governments. Projects are being built across the country. But the long-term success of green infrastructure depends on its integration with land use, site design and architectural decisions. Increasingly, municipal planners and officials are being asked to work with water management professionals to address the following challenges:
Aligning land use and site planning decisions to help site and manage systems on public and private property not under the direct control of the agency directly responsible for water resources;
Gaining regulatory and budgetary approvals for a technology that often relies on innovative engineering, soil mixes and biological processes in a diffused series of smaller projects; and
Accounting for significant co-benefits, including community amenities and air quality improvements that are difficult to monetize and monitor.
This report summarizes green infrastructure practice and presents nine successful ways by which planners and policy makers are integrating this innovative technology with land use and site planning decisions. These include measures to secure space for green infrastructure, find the funding to pay for construction and management and rethink management responsibilities.
