Green Infrastructure Toolkit


Regulatory Tools

Regulatory tools include requirements set in zoning or building codes or stormwater retention ordinances, mandating action by private property owners. In many jurisdictions, stormwater retention ordinances establish retention requirements and then lay the foundation for other regulations that mandate green infrastructure as a specific set of practices to meet those retention requirements.

Regulatory tools, because of their inherent nature as requirements (as opposed to options or incentives), get surer results than programs that rely solely on capital improvement projects on publicly owned lands or voluntary measures for private land.  Private property owners must meet regulatory requirements to obtain a permit and, therefore, they must change their landscaping and building practices to comply. As a result, regulatory approaches may result in some political pushback. Many of the regulatory tools below may be more palatable to local developers if some flexibility is built into the system. For example, Seattle’s stormwater ordinance allows some retention offsite if retention is not practical onsite,See footnote 1  while the District of Columbia’s ordinance allows for payment of a fee or purchase of stormwater credits as alternative methods of meeting its retention obligation.

Last, because of the nature of regulatory requirements as things mandated in laws such as zoning codes or other ordinances, many of these strategies may require legal changes to incorporate those requirements into that particular legal framework. These legal changes can be administratively complicated and time-consuming.

Zoning Codes

Zoning codes can create green infrastructure requirements for new construction and sometimes substantial renovations. Zoning codes are particularly suited to tailoring those requirements to particular land uses such as industrial, residential, etc, and for addressing the entire site under development, including landscaping (in contrast to building codes, which generally focus more specifically on the buildings. Zoning requirements can either set retention requirements that property owners can meet by choosing green infrastructure practices themselves, or can enumerate particular green infrastructure practices that qualify to meet the regulatory requirement. Each local government will need to look at the authority given by its state government to enact zoning regulations in order to determine how strong that local government can make green infrastructure requirements.

Building Codes

Building Codes can similarly create green infrastructure requirements for new construction and sometimes substantial renovations. In contrast to zoning codes, however, building codes are particularly suited to tailoring requirements to particular building types regardless of the use – for example, single-family residential, office buildings, etc.  Different states grant different authority to local governments for building codes; some states require local building codes to conform to state standards, while other states give local governments wide latitude to create their own standards.See footnote 2 Each local government will need to look at the authority its state government has given it over building codes in order to determine how strong that local government can make green infrastructure requirements.

Stormwater Ordinances

Stormwater Ordinances can directly require green infrastructure practices, as Binghamton, NY’s, ordinance does, or can serve as a foundational regulation to encourage green infrastructure to meet retention requirements. Stormwater ordinances can link these practices to reductions in stormwater fees (see incentive-based approaches), or can simply require retention and/or green infrastructure practices. Like zoning and building codes, stormwater ordinances best reach new construction projects, although they can impact existing buildings when those buildings are undergoing substantial renovation. Unlike state-level authorizing statutes for zoning and building codes, authority delegated to local governments to enact stormwater ordinances can be found in any of several sources, including authority to enact zoning codes, erosion control ordinances, and subdivision regulations.


Related Resources

New Orleans Comprehensive Zoning Ordinance, Article 23: Landscape, Stormwater Management, and Screening

New Orleans Comprehensive Zoning Ordinance directly addresses landscaping and stormwater management. Article 23 of the CZO includes several elements that require or strongly prefer green infrastructure practices to manage stormwater in parking lots, including bioswales, pervious pavement, and green roofs. For example, every parking facility is required to capture, filter, infiltrate, or store the first 1.25 inches of stormwater. Section 23.12 outlines various Best Management Practices (BMPs) which minimize runoff, increase infiltration, recharge groundwater, and improve water quality. These include bioswales, constructed wetlands, detention basins, ditch gardens, sand filters, and tree protected areas. The CZO does not prescribe the use of any specific BMP, but describes them with the goal of providing guidance. 

Building a Better Norfolk: A Zoning Ordinance of the 21st Century - Norfolk, Virginia

This Norfolk Zoning Ordinance adopted in January 2018 includes a Resilience Quotient System where development is required to earn a certain number of points, based upon size or number of units, by including different resilience measures in the design of the project.  Stormwater management is one component where new developments and redevelopment projects must earn points.  Points can be earned for installing a green roof, rain-gardens, or other stormwater infiltration systems; using pervious paving systems; providing a community-garden space; preserving pre-development natural, native vegetation; providing for new tree-planting;and/or preserving large non-exotic trees on site. Development projects must show how they are incorporating resilience measures through the site-plan review process and at least one point must be earned for stormwater management measures.

District of Columbia Green Area Ratio - Zoning Regulations

The District of Columbia (Washington D.C.) Green Area Ratio (GAR) is an environmental sustainability zoning regulation which sets requirements for landscape elements and site design to help reduce stormwater runoff, improve air quality, and mitigate urban heat. The GAR sets minimum lot coverage standards for landscape and site design features to promote greater livability, ecological function, and climate adaptation in the urban environment. The GAR requirements provide a firm retention target and allow local governments to weight the elements they prefer in order to influence behavior, while providing some measure of flexibility for property owners.

Boulder Green Building and Green Points Program - Boulder, Colorado Municipal Code Chapter 7.5, Ordinance 7565

Boulder, Colorado’s municipal building code integrates Ordinance 7565 (Green Building and Green Points Program) which was adopted by Boulder City Council on Nov. 13, 2007 and went into effect on Feb. 1, 2008. The Boulder Green Points Building Program is the nation’s first mandatory residential green building program that requires a builder or homeowner to include a minimum amount of sustainable building components based on the size of the proposed structure. 

Applicants are required to earn “green points” which are generated from adaptive strategies/sustainable practices in landscaping, shading of hardscape (trees), surface water management, high efficiency irrigation, waste management and building rehabilitation. For example, preserving existing mature trees on site earns one point per tree, up to a maximum of five points.

Points are also awarded for stormwater management practices, such as installing permeable surfaces. The number of points earned is based on the percentage of the site that is permeable, up to four points for a site that is 100% permeable.  Applicants must reach a certain number of points (depending on type of project and square footage) in order for the project to be permitted.

New York City Zoning Code - Permeable pavement requirements

Since 2007, New York City’s zoning code has required parking lots for community facilities to allow permeable pavements where appropriate. 

Parking lots at community facilities must capture stormwater through larger perimeter plantings and planting islands than is required for other parking lots, and the facility lot must be properly graded to drain runoff to those plantings. Both types of plantings must include trees of a certain diameter and spacing, and all vegetation must be from a list of pre-approved species. The objectives of these zoning requirements are to better manage stormwater on parking lots and reduce urban temperatures by providing shade.

Buffalo, New York, Green Code Unified Development Ordinance, Article 7.3.4 Best Management Practice

The City of Buffalo, New York’s Unified Development Ordinance now includes a Green Code that requires use of green infrastructure best management practices (BMPs) wherever practical to achieve the Code’s performance-based stormwater retention standards. The ordinance, at Article 7.3.4 of Section 7 on Stormwater, specifies infiltration on-site using bioswales, rain gardens, and other strategies; or stormwater capture and reuse through cisterns, green roofs, and other strategies. The ordinance clarifies the order of preference for stormwater management facilities utilizing BMPs, prioritizing conservation of natural areas before on-site infiltration practices, and on-site infiltration practices before capture and reuse practices. 

Washington D.C./District of Columbia Stormwater Ordinance - 2013 Rule on Stormwater Management and Soil Erosion and Sediment Control

In 2013, the District Department of the Environment (now D.C. Department of Energy and Environment, or DOEE) released an amended Rule on Stormwater Management and Soil Erosion and Sediment Control to require that major development and redevelopment projects  incorporate additional measures to retain stormwater and reduce runoff. The District offers compliance flexibility by allowing for some off-site retention, the ability for developers to pay an in-lieu fee, or the option to buy stormwater retention credits. The District also developed a Stormwater Management Guidebook (SWMG) to provide technical guidance on stormwater best management practices (BMPs) and how to comply with the rule. The amended 2013 Stormwater Rule and SWMG are designed to improve water quality and reduce runoff to the Anacostia and Potomac Rivers, Rock Creek, and their tributaries. Green infrastructure practices can also help reduce risks from climate impacts by reducing urban drainage flooding and urban heat.

City of Binghamton, New York Erosion Control Ordinances

The City of Binghamton, New York’s erosion control ordinances require property owners seeking permits for construction to submit an Urban Runoff Reduction Plan (URRP) to demonstrate how they will manage stormwater after construction.  The URRP must show how the development will manage a 10-year, 24-hour storm event and include green infrastructure techniques.  Like Seattle Washington’s stormwater ordinance, the clear requirement to include green infrastructure takes the code beyond simple retention, specifying the best management practices (BMPs) that the city most wants to see, such as green roofs.  

City of Seattle, Washington Stormwater Code

The City of Seattle, Washington’s stormwater regulations are implemented in order to improve stormwater management for new development in Seattle, including on-site stormwater management. Seattle’s Stormwater Code imposes retention requirements on residential properties.  These requirements vary according to several factors, including the type of sewer system or water body to which the site discharges and the size of the land disturbance or impervious surface on that site.  For example, if a parcel discharges into small lake basins and its total new-plus-replaced impervious surface is 2000 square feet or more, it must manage stormwater from a 25-year rainfall event (a storm that has a 4% chance of occurring in any given year). Additionally, construction sites are required to maintain natural drainage patterns, protect downstream properties from erosion, and implement green infrastructure, to the maximum extent feasible.

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