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Minnesota Stormwater Manual

Planning green stormwater infrastructure projects and practices
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This green stormwater infrastructure (GSI) planning guidance was created to

  • help practitioners plan for incorporating green stormwater infrastructure in their communities,
  • help make the case for green stormwater infrastructure,
  • provide resources on how to fund and finance green stormwater infrastructure, and;
  • provide information on how to include green stormwater infrastructure into ordinances and policy.

Much of the information presented here is geared towards practitioners who are new to GSI planning and is intended to provide an overview of the topics and questions that are relevant in the GSI planning process.

How to Plan for Green Infrastructure in Your Community

This section provides information on the types of topics to consider when planning for green stormwater infrastructure in your community.

Defining Goals and Objectives

When planning GSI for your community, an important first step is to define the community’s goals and objectives. Every community is unique and therefore every GSI plan also unique. Goals and objectives should be defined with as broad of a partnership or stakeholder group as practical. It is the stakeholders who will ultimately judge the success or failure of a project, so engaging them early and often will help ensure a successful outcome. Example goals and objectives could include:

Considering the Scale of GSI Planning

An important consideration of GSI planning is to define the scale of the project and to understand whether the objectives of the project are designed to meet site-specific improvement goals, local community goals, broader regional goals, or some combination. In addition to any local benefits, individual GSI practices can also contribute positively to large-scale downstream water quality objectives such as a Total Maximum Daily Load (TMDL) or in-stream water quality targets that aim to reduce pollutants such as phosphorus, nitrogen, sediment, or chlorides. Most regional stormwater or water quality goals, for example, have their own planning documents (Watershed Restoration and Protection Strategies, TMDL Implementation Plans, etc.) that may help define the need for site-specific GSI.

The table below provides an overview of common plans that could inform or be developed during the GSI planning process at various different scales. This table has been adapted from the Credit Valley Conservation and Toronto and Region Conservation Authority and modified to include common Minnesota-specific planning documents (CVA & TRCA, 2010).

Sequencing of Events for GSI Planning

The planning process for a GSI project can follow many different paths, however, the following steps are typically part of the planning process. First, goals and objectives are determined to meet environmental, social, and economic needs. Next, the possible GSI approaches are evaluated for technical and financial feasibility. Lastly, guided by the goals and objectives, and the range of technically and financially feasible GSI solutions, a site-specific GSI design is conducted. Throughout this process, partnerships with key stakeholders are created, consulted, and used to maximize the chances of successful GSI planning and implementation. Public outreach is typically also conducted throughout the entire process to garner public support of the project.

Length of Time Needed for GSI Planning

The length of time, or the amount of time, needed for GSI planning can vary from project to project, and is often dependent on the type of GSI project.

GSI planning and implementation on land-development projects (e.g., new development or large redevelopment projects, street reconstruction projects, and master plan development) can take one to several years to realize, depending on the pace of the land development project. This type of GSI planning is often the most successful and cost-efficient since the GSI planning can be incorporated early in the planning and design phase of land-development projects. Ideally, this results in GSI practices that are seamlessly integrated into the landscape and infrastructure of the project.

GSI planning also often occurs as retrofit projects (e.g.: adding green stormwater infrastructure to an existing landscape). GSI planning and implementation of retrofit projects can take 6 to 18 months to realize, sometimes longer if unforeseen roadblocks occur. Retrofit projects typically come at a higher cost relative to projects that are integrated into land development projects. Mobilization and other labor costs associated with retrofit costs can be minimized if GSI retrofits are planned to happen in conjunction with other infrastructure improvement projects, such as pavement repairs or regrading. Advanced and comprehensive GSI planning projects are one strategy to save retrofit costs by identifying opportunities to install GSI alongside future capital improvement projects. The Towerside District Stormwater Project, an initiative by the Mississippi Watershed Management Organization, illustrates this concept in this video.

Technical Approach and Resource Needs

The technical approach and design process will vary from project to project but may generally follow a sequence of events described by the Credit Valley Conservation and Toronto and Region Conservation Authority (CVA & TRCA, 2010). The table below shows this sequence and also identifies the type of personnel resources that could be used, as well as helpful publicly available technical resources to help GSI planners get started.

GSI practices need to be designed by duly licensed professionals, such as a professional engineer or landscape architect. In addition to the personnel resources listed in the table above, additional types of personnel that could be consulted include:

  • Easement and realty specialists
  • Financial planners and/or accountants
  • Meeting facilitators
  • Regulatory & permitting specialists
  • Zoning planners
  • Legal counsel specializing in drafting ordinances
  • Arborist or restoration specialists
  • Marketing specialists
  • GSI Installers
  • Surveyors

Communities should determine which of these personnel resources they have “in-house,” and which could be provided by consultants. Ideally a planning team would include both in-house resources who have an intimate understanding of the community priorities & resources and consultants who can bring a range of experiences and skills from other projects and communities.

Financial Considerations

Financial considerations will be a foundational topic for GSI planning efforts. Based on the stated goals, objectives, and available community resources, the financial priorities and strategies can look quite different for each community.

The three key financial considerations are: cost, return on investment (value assessment), and funding.

  1. Cost: Cost considerations include planning, design, installation, and operations & maintenance costs. These costs can be assessed by the design and planning teams.
  2. Return on Investment: A value assessment factors in both the direct performance benefits of GSI practices and the ancillary community benefits of such practices. Direct performance benefits can be measured or estimated and include, for example, volume of runoff managed, pollutant load reduction achieved, or carbon reduction. These can be measured via monitoring or sampling programs, or estimated via engineering tools and models. Ancillary benefits are harder to measure directly and include, for example, improved air quality, impact on pollinators, climate change resiliency, and traffic calming. These benefits are more difficult to quantify directly, and a relative ranking/scoring strategy is typically used. This assessment is best conducted by all of the planning partners so as not to skew the results.
  3. Funding: Funding is a universal and continuously evolving challenge for GSI projects. There are many funding strategies which can be considered. These are discussed in the “How to Fund and Finance GSI” section. Funding considerations are best assessed by the GSI management team with support from the design team.

Community priorities are as unique as the communities themselves. Most communities and stakeholders prefer funding GSI projects that provide direct and ancillary amenities. For example, funding a bioretention practice that is also a sidewalk pocket flower garden may be more attractive to the community than replacing the impervious pavement of an alley with permeable pavers, even though both the bioretention and permeable pavers provide similar direct stormwater-related benefits. With this in mind, consider pairing GSI projects to community amenity projects to increase the likelihood of funding and community support. Pairing or grouping projects can also increase the overall cost-effectiveness.

Permitting and Approvals

There is typically a permitting and approval aspect to installing GSI. Authorities will vary depending upon the location and extent of the project, but may include:

  • Stormwater utility (e.g., municipality or watershed district)
  • Watershed districts or watershed management organization
  • Gas and electric utility (approval from utilities is required if digging is involved)
  • Zoning and Homeowners Associations
  • Departments of Transportation (if the public right of way is involved)
  • City or county

Including key people from these organizations as planning partners can be helpful in obtaining the right permits and approvals when implementing green stormwater infrastructure. Contacting the city, county, or watershed district can be an effective place to begin the permitting process.

The permitting and approval process can be lengthy, so it is helpful to begin the permitting process early. For authorities in which there is an overlap in their permitting processes, it is beneficial for communities to work with these authorities concurrently.

Establishing Partnerships

The most effective way to plan and implement a GSI project is to create a diverse group of partners group. Partnerships help increase community involvement, provide technical expertise required to meet goals, and can help create a maintainable GSI system. Partnerships can also sometimes augment the available funding and resources through in-kind contributions or additional funding. GSI partners can be loosely grouped into three categories: managers, design teams, and stakeholders. GSI planning efforts should include representatives from all three categories.

  • GSI managers may include owners, maintenance personnel, planners, developers, and regulators. GSI managers may be part of private, government, or non-government organizations.
  • GSI designers may include engineers, scientists, and landscape architects that are specialized in GSI and natural restoration practices. If one of the GSI goals is to use GSI practices to provide community amenities, then the inclusion of a landscape architect is strongly encouraged. Landscape architects are trained to identify end user needs and design infrastructure to provide a desirable user experience, all while achieving the technical goals of a design. Designers may be municipal staff or outside consultants.
  • GSI stakeholders may include adjacent property owners, adjacent infrastructure managers, community organizations, government leaders and officials, and anyone who may access or see the GSI. The role of stakeholders in the GSI planning process is integral as they will ultimately judge the success of the GSI, so stakeholder engagement should be prioritized in the early planning phases. To cultivate an effective relationship with stakeholders, a stakeholder engagement plan should be developed and may include:
    • Identification of audiences
    • Stakeholder roles and responsibilities
    • Communication strategies
    • Timing of engagement for individual stakeholders based on roles and responsibilities

Public Outreach and Communication

As stated in the previous section, it is the stakeholders who will ultimately judge the success or failure of a project, so engaging early and often will help ensure a successful outcome. Public outreach is particularly important when defining community goals and priorities.

Outreach activities can be done in-house or via a consultant. The role of public outreach is often undervalued, and the effort required is often underestimated. When in doubt, a professional specialist, such as a communications or public relations expert, is recommended to support public outreach.

Many communities have existing resources and strategies for public outreach. Surveys, council meetings, mass mailings, newspapers and print media, social media, public bulletins, and public meetings are common outreach strategies. Most communities and neighborhoods may have one or several primary mechanisms for community notification which can be leveraged. Note that GSI may be unfamiliar to many, so use language that is accessible, clear, and jargon-free when discussing GSI and its challenges and benefits.

The outreach materials are equally as important as the outreach strategies. Interactive communications materials can be highly effective to support outreach strategies, are increasingly common and relatively easy to do, and keeps the public interested and engaged. Examples of interactive communications materials include:

  • Storyboards (e.g.: USACE Engineering With Nature storyboards)
  • Online Story Maps (e.g.: City of Atlanta GSI Program storymap)
  • Online web maps (e.g.: NYC DEP Green Infrastructure Program Map)
  • Website content (e.g.: Philadelphia GSI webpage)
  • Targeted priorities boards
  • Commenting on maps using post-its
  • Public interviews and surveys
  • Video booths
  • Interactive physical models

In addition to well-crafted media content and notification, few techniques are as effective at communicating the benefits of GSI as having the public walk by and through a built example of GSI. Creating high-visibility GSI pilot projects at public facilities such as government offices, schools, or libraries, can be an effective means of engaging and educating the public on GSI. Pilot projects can include educational signage about the function and benefits of GSI, and allows the public to see GSI under different weather conditions and seasons. GSI pilot projects at schools can also be incorporated into the educational curriculum.

Accounting for Climate Change and Resilience

In Minnesota, the annual rainfall depth and frequency of large storms has been increasing in recent years (MNDNR, 2021). GSI can be a valuable tool to help offset runoff generated from more precipitation, but planners may want to design these practices to manage the higher flow rates and volumes associated with larger storms. With increasing rainfall and runoff, as well as with the general trend of increasing imperviousness, the target stormwater quality treatment volume may need to be increased as well. For example, in Austin, TX a site with 50% impervious cover is required to treat the first 1-inch of precipitation, but sites with 100% impervious cover are required to treat the first 1.5-inches of precipitation (Franke, 2016).

Minnesota’s winter temperatures also have increasing (MNDNR, 2021), consequently more frequent “mid-winter thaws” can be expected, which can impact the proper functioning of infiltration-based practices in particular. For example, freezing and thawing events will impact infiltration in aboveground retention systems with surface conveyance differently than underground retention systems with subsurface pipe conveyance. Properly designed infiltration-based practices should function during winter; however, the efficiency of saturated, frozen infiltration practices can be greatly diminished. Mid-winter thaws may increase the likelihood that infiltration practices are saturated in near-freezing weather, which may render them less effective during the spring runoff events. If the goal of a GSI practice is to infiltrate the spring melt water, then increasing the stormwater retention capacity of the practice may be warranted.

A diverse and preferably native plant palette should also be considered in order to make the overall planting bed more resilient to a broader range of climate and hydrologic scenarios. Installing GSI can help reduce local temperatures associated with climate change, and drought resilient species can help maintain effective ecosystem function during drier periods. More planting guidance can be found in the Minnesota Plant List page of the Minnesota Stormwater Manual.

Potential Roadblocks and Barriers

There are many potential roadblocks and barriers to GSI implementation, but in many cases, these can be anticipated and managed. Below is a list of common roadblocks experienced by GSI planners and suggested ways of addressing or managing these roadblocks.

  • Lack of Community Buy-In: The value and benefit of green stormwater infrastructure are not always readily perceived or understood by community members or stakeholders, which sometimes prevents acceptance or support of GSI efforts. Communicating the benefits of GSI beyond stormwater management, and focusing more on ancillary benefits of GSI, is an effective method for overcoming this particular challenge. Incomplete or inadequate representation of these benefits may leave stakeholders unhappy with value gained from the GSI. Plain language should be used when describing the benefits and mechanisms of stormwater management to community members. Using visuals and graphics can also be an effective means of communicating with community members. Examples of interactive techniques that can be used to communicate with the public are shown in the Public Outreach section.
  • GSI Costs are Deemed Too Expensive: Costs are a clear roadblock when planning and implementing GSI. Early in the planning process, planners and partners should provide rough cost estimates to set expectations and allow for funding and financing options to be explored as soon as possible. Clear communication on all the benefits of GSI can also help demonstrate and justify the cost of GSI and can help alleviate cost concerns from partners and stakeholders.
  • Unclear Operations & Maintenance Responsibilities: Ongoing maintenance is necessary for GSI to operate properly and provide all intended benefits. Failure to properly maintain GSI can lead to expensive repairs. GSI O&M can add a continued expense over the lifetime of the GSI practices; however, these costs can be less than maintenance of traditional gray infrastructure. Ongoing maintenance agreements are always recommended and, in some cases, necessary. More information on GSI operation and maintenance can be found in the O&M of GSI BMPs page of the Minnesota Stormwater Manual.
  • Uninterested Owner: Occasionally, a land or building owner may not be interested in participating in a GSI project. Landowner approval or buy-in should be sought as early as possible during the planning process so that alternatives can be identified if necessary. Clear communication on all the benefits of GSI can also be helpful. Some landowners may be interested in participating in water quality trading.
  • Lack of Commitment After Design Stage of Project: Sometimes design components that are included in early project renderings are dropped after the project has been approved and permitted. Consider retaining commitments to the design through the approval process and beyond.
  • Competing Resources and Priorities: In addition to monetary resources, available time from those stakeholders and partners with critical skillsets can derail progress on GSI planning. To the extent possible, only partners that have the time and capacity to stay actively and sufficiently engaged throughout the entire planning process should be selected. Timelines should be developed to accommodate competing priorities so that delays are avoided, and expectations are set appropriately.
  • Concerns About GSI Aesthetics: Certain GSI may not meet the aesthetic preferences of all stakeholders, particularly those who may interact with a practice. The end user should always be considered, and design features should incorporate their feedback and preferences. Alternative GSI types may help offset aesthetic concerns, but not always. Early buy-in from stakeholders can also minimize this roadblock.
  • Concerns About GSI Effectiveness: Stakeholders may question the effectiveness of GSI related to stormwater volume or pollutant load reductions. This may be a general concern (uncertainty in the literature values) or due to site-specific modeling that shows GSI may not achieve the desired objectives. In both situations, open communication between all partners, and particularly the design team and managers, should be encouraged. The team as a whole should reach a consensus based on the best available information. Proper installation is critical to GSI effectiveness. Third party oversight and inspection are helpful to ensure proper installation of GSI, which will help achieve maximum potential efficiency.
  • Regulatory Hurdles: Regulatory hurdles may slow down or derail the GSI planning, and as such can be disincentive to certain stakeholders. Experienced engineers, planners, and other partners should be included from the onset of planning to make the regulatory process as streamlined as possible. Clear communication between the party that owns or is implementing the regulatory process and the regulator is encouraged. The permitting and approvals section has additional information on potential permitting and approval requirements for GSI.

Additional information on overcoming barriers to green stormwater infrastructure is also available on EPA’s website at https://www.epa.gov/green-infrastructure/overcoming-barriers-green-infrastructure.

Key Questions to Consider During the Planning Phase

There are a lot of questions to be answered during the planning phase of the GSI project, particularly in the early stages. Even if a planning team is experienced, the total unknown information may be a roadblock itself. The table below is intended to categorize the key questions and topics that should be asked and considered throughout the design process.

How to Make the Case for Green Stormwater Infrastructure

General overview

Planners and engineers who would like to integrate GSI into landscapes and projects sometimes find themselves having to “make the case” for GSI. This may include presenting on the multiple benefits of GSI (social, economic, and environmental), describing the equity and environmental justice aspects of GSI, and discussing cost related topics such as life cycle costs, triple bottom line, and cost-benefit analysis. Different outreach and communications strategies can be used to help “make the case,” as discussed in the “Public Outreach and Communication” section.

Presenting the Multiple Benefits of GSI

Green infrastructure should be presented as not only providing stormwater benefits, but also as providing multiple social, economic, and environmental benefits. Considering and presenting these benefits together rather than separately, and highlighting the interactions between benefits, is important in making a better business case for implementing green stormwater infrastructure.

The social benefits of GSI are numerous, ranging from saving lives to enhancing the aesthetics of a neighborhood. Green infrastructure can be integrated into the creation of public amenities such as pocket parks or micro green spaces. GSI can also improve overall public health by reducing air temperatures in the summer (counteracting the urban heat island effect), improving air quality, and decreasing asthma incidences, and stimulate a more inviting and walkable environment (USEPA, 2017). Secondary cascading impacts such as transportation delays, utility service disruptions, and even pandemics are also times when GSI can have a positive effect: waiting for a late bus under the shade of street trees on a 95℉ day or a stroll through a city park for moments of socially distanced relief during the recent Covid pandemic are relatable moments. Social equity challenges are highlighted in low- to moderate-income communities and urban neighborhoods, which often have more impervious areas than tree cover (New York Times, 2020) and older, traditional stormwater management infrastructure. Deploying GSI in the form of street trees, urban forests, and integrated stormwater management can provide traditional infrastructural service benefits while also satisfying the innate human instinct to connect with nature. Placing GSI in urban areas increases the likelihood that a greater diversity of people gets time in and around natural systems. If planned properly, strategic GSI placement can help provide socially equitable access to green spaces for all residents. In identifying the social benefits of GSI, a community should also address the role GSI plays in gentrification and should consider these unintended social consequences in the design and placement of GSI. Refer to the Equity Section for further information on the role of GSI in gentrification and tools for addressing it.

Economic benefits of GSI include reduction of O&M costs relative to traditional infrastructure, reducing the initial capital outlay costs of large traditional (gray) infrastructure, preserving property values, supporting local workforces, and even agri/eco-tourism. While GSI does require careful maintenance as discussed in the Potential Roadblocks and Barriers section, GSI tends to appreciate in value over time as the ecosystems protected or created - such as rain gardens, bioswales, and constructed wetlands - increase in functionality. This is an advantage over traditional gray infrastructure, which tends to depreciate over its lifetime (The Nature Conservancy / AECOM, 2021), resulting in the need for major repairs or replacement. Green roofs are an example of building-integrated GSI which can minimize traditional building component replacement cycles and extend the life of components - in this case sheltering roofing membranes by limiting exposure to damaging ultraviolet rays. Other examples include GSI techniques such as onsite stormwater capture and infiltration with rain gardens, bioswales, and constructed wetlands which can reduce the need for large, complex, costly, and often unattractive traditional stormwater management structures such as concrete detention basins, hardscaped bypass channels, and below-grade catchment tanks which require expensive excavation and relocation of utilities to install (Conservation International, 2019). Planting chloride-tolerant species reduces the replacement costs from deicing salts. Maintaining - and even increasing - property values have been shown to be a positive secondary benefit of GSI related to social benefits listed above: people and businesses value being located in and near vegetation and green areas. Designing, building, operating, and maintaining GSI cannot be outsourced: these are local jobs done by local people, keeping dollars in the community (FEMA, 2021). Finally, treating agricultural, preservation, and reservation lands as green stormwater infrastructure extends the possibility of economic benefits of agri/eco-tourism into non-urban areas.

Environmental benefits from GSI include improvements in water quality, air quality, greenhouse gases, and ecological habitat, and reduced impacts from flooding, extreme precipitation, extreme heat, wildfire, and other climate stressors such as landslides, mudflows, and subsidence (FEMA, 2021). Integrated stormwater management with GSI retains and treats storm water locally, reduces the need for extensive and often oversized drainage systems, reduces exposure of stormwater to surface pollution like road salts and oils, and can reduce occurrences of localized flooding. GSI can also help mitigate greenhouse gasses and help reach increasingly aggressive state and local targets through carbon sequestration. Carbon sequestration can happen on small urban lots by planting and preserving deep-rooted and woody-stemmed native plants and trees on small urban sites, suburban lots, and in rural forest, wetland, and meadow areas. Regenerative agricultural practices – crop rotation, no/low till, intercropping, integration of deep-rooted grasses (and other prairie plants), and biochar – can further extend carbon mitigation potential of agricultural lands (Project Drawdown, 2021). From pollinator gardens to constructed wetlands, GSI not only increases the number and diversity of types of habitats for different species of plants and animals through habitat creation, but it also increases ecological connectivity across urban, suburban, and rural areas through habitat preservation. With elevated annual precipitation and frequency of heavy rains in Minnesota, the risk of flooding is likely to increase (MNDNR, 2021). GSI can manage flood risk by reducing stormwater runoff through infiltration practices (e.g., bioswales) (USEPA, 2022a). NOAA provides A Guide to Assessing Green Infrastructure Costs and Benefits for Flood Reduction. Green infrastructure can include water elements or solar elements to implement blue-green and yellow-green stormwater infrastructure, respectively, in a community which can provide additional water quality, energy, and aesthetic benefits.

Social, economic, and environmental benefits should also be considered holistically rather than separately. Consider all benefits categories and set goals to achieve high marks across the board. For example, integrated stormwater management with GSI keeps water onsite locally, provides an attractive landscape (social), reduces the need for oversized traditional water treatment infrastructure (economic), and creates pockets of ecological habitat and shading (environmental). Also consider the interactions between benefits and use the process as an opportunity to innovate. Workforce development and equity are closely linked, for example. Implementing green stormwater infrastructure in disadvantaged communities is critical as discussed above, but the design, installation, operation and maintenance of green stormwater infrastructure also presents further opportunities to reduce barriers for entry for local builders from historically disadvantaged populations. Consider tailoring training programs in GSI for O&M staff, small businesses (especially (MBE / DBE / WBE), trade / vocational schools, and community colleges. Developing training for older staff and contractors familiar only with traditional infrastructure will improve job retention, prioritize continuing education, and encourage broader uptake and acceptance of green stormwater infrastructure.

Equity

When planning for GSI, equity issues may arise. For example, GSI initiatives tend to favor locations where open space or vegetation already exists, or in affluent neighborhoods. The planning phase of GSI can be used to assess where GSI is most needed and prioritize GSI in environmental justice (EJ) areas. Also consider linking GSI incentives to flood mitigation programs and focus on locations already experiencing flooding and extreme temperatures, which typically coincide with EJ areas.

Another common equity issue is lack of a diverse stakeholder group involvement during the GSI planning stages. Engaging stakeholders from a variety of backgrounds and expertise to maximize potential project benefits and buy-in is critical for the success of GSI (The Nature Conservancy / AECOM, 2021). Involving a diverse group of community members can occur at all GSI stages, including planning, designing, building, and monitoring green stormwater infrastructure. Consider historically disadvantaged populations, income-limited, or other vulnerable groups such as the elderly, small-to-medium enterprises (SME), low-to-medium income (LMI) households, single-parent households, and renters; and populations at increased risk of climate change impacts.

To engage a diverse group of stakeholders, consider the barriers to community engagement, such as work schedules conflicts, limited transportation options, or cost of attendance. Providing incentives such as compensating stakeholders for their time, reimbursing travel costs, or planning engagement opportunities outside of traditional work schedules can be very helpful in attracting a diverse group of stakeholders. Be intentional and considerate when entering relationships with community members and be mindful of mistrust based on historic environmental racism and redlining, as well as the impact of gentrification on the community and the contribution to gentrification by GSI. Meet people where they are, early and often, by conducting outreach in community locations such as libraries, community centers, schools, churches, and parks. Leverage relationships with local groups, partners, and organizers who know the community. Demographic research can also be used to identify the desired composition of a stakeholder group.

Another equity concern is that newer GSI design, construction, installation, and maintenance may present barriers for market-entry for local builders from historically disadvantaged populations and communities without training. This population can be targeted for specific communication on GSI work opportunities for smaller construction firms typically owned and operated by income-limited or vulnerable groups such as small-to-medium enterprises (SME). Consider encouraging local trade schools and career centers to provide training on GSI design, construction, installation, and maintenance training. Communities can also provide incentive and/or subsidy programs to small-to-medium enterprises (SME), low-income homeowners, and landlords for GSI implementation. These incentives could include access to technical assistance and financial incentives, including tax rebates, subsidies, and permit waivers or expedited permitting.

Additional resources for addressing equity and environmental justice in GSI planning include:

  • The University of Minnesota toolkit on investing in green stormwater infrastructure as means of improving equity among communities
  • EPA Equitable Development and Environmental Justice


Life Cycle Costs, Triple Bottom Line, Cost-Benefit Analysis

Green infrastructure can be a cost-effective approach to reduce stormwater flows, improve water quality, and help communities stretch their infrastructure investments further by providing multiple environmental, economic, and social benefits also known as the triple bottom line (USEPA, 2022b). Making the case for GSI often entails comparing life cycle costs or cost-benefit analysis between green and grey infrastructure, or between different types of GSI. Cost considerations should include the upfront capital costs as well as the long-term maintenance requirements and replacement costs over the expected life span of the infrastructure.

Many guidance documents and tools exist to assist planners and engineers calculate life cycle costs, assess the triple bottom line, or conduct a cost-benefit analysis, including:

It is also worth noting that entities implementing GSI may want to consider collecting their own long-term performance and life-cycle cost data to improve their decision-making process in the future.

How to Fund and Finance Green Stormwater Infrastructure

Funding GSI can be a considerable roadblock for a planner or community. Financial constraints and funding opportunities should be understood at an early stage of planning. Fortunately, there are many federal, state, and other grant opportunities that can be leveraged to help finance GSI.

Federal funding opportunities are diverse - they come from numerous agencies and target many types of benefits. Given the variety of GSI benefits (e.g., water quality, flood management), GSI is applicable to many opportunities. EPA maintains one such list of applicable funding sources.

At the state level, MPCA maintains a page devoted to state funding options. MN’s Clean Water Fund has funded over 3,300 projects with the mission of improving and protecting surface water resources.

Local governments also fund projects through stormwater fees or other infrastructure funds. Contact municipal and county governments for local opportunities. Municipal bonds and private financing are other opportunities for funding.

A non-exhaustive list of current funding opportunities is provided in the table below. It should be noted that some of the funding resources provided may be only loosely connected to GSI but may be worthwhile to explore as GSI may be used to accomplish their overarching goals.

How to Include Green Stormwater Infrastructure Into Ordinances and Policy

General Overview

Ordinances and policies are effective tools to assist municipalities in implementing green stormwater infrastructure in a consistent and integrated way (EPA, 2021). Green infrastructure and stormwater ordinances are becoming widespread across the United States as communities and the public are realizing the environmental, social, and economic benefits of these ordinances. The Missouri Department of Natural Resources created a flow chart that shows the types of policies and ordinances that can help control stormwater runoff and promote green stormwater infrastructure (Figure 1).

Ordinances should clearly identify the objectives and performance goals. Some communities develop ordinances and engineering or design guidelines at the same time. This can help streamline implementation and provide practitioners with the necessary tools to follow the ordinance requirements. The objectives and performance goals of an ordinance can vary widely depending on what a community would like to achieve. Some examples include protection of existing trees, reduction of post-construction stormwater volume and peak flows, promotion of native vegetation, and reduction of impervious surfaces.

Some communities may provide alternatives to ordinances in order to promote green stormwater infrastructure, such as green stormwater infrastructure incentive programs. These typically consist of some kind of monetary rebate to install green stormwater infrastructure. Rebate or incentive programs can be specific and target specific geographic locations, types of buildings, or types of green stormwater infrastructure. Examples of other alternatives include zoning codes or building codes that require green stormwater infrastructure for new construction or renovations.

General Process

Developing ordinances typically requires collaboration across multiple city departments. The request for an ordinance can be initiated by an entity who is responsible for green stormwater infrastructure and/or stormwater, or an entity who has authority over the land on which green stormwater infrastructure would be implemented.

Developing ordinances requires strong stakeholder support in order to be accepted as well as City Council support. Stakeholders can include individuals, trade organizations, or public interest groups. The stakeholder process can be time and resource intensive, but a successful stakeholder program can be helpful in successfully developing ordinances. The entity’s legal team should review any proposed ordinance to make sure the ordinance is aligned with local, state, and national laws. Ordinances may also need approval from municipal councils, boards, or the public. Developing ordinances can be done using in-house resources, although outside expertise can be brought in for technical, outreach, communications, or legal support.

Developing ordinances may take anywhere from several months to several years, depending on the intended reach of the ordinance and the support from the affected community. Common obstacles to implementing ordinances include stakeholder opposition, competing ordinances (e.g.: an ordinance on minimum sidewalk could compete with an ordinance for larger tree boxes), and lack of support from municipal leaders.

Unintentional Barriers

Current codes and ordinances may create unintentional barriers to the implementation of GSI due to outdated regulations or unclear language that limit the application of key GSI runoff mitigation measures. Some of these barriers include:

  • Dimensional standards
  • Requirement of sealcoating paved surfaces
  • Landscaping buffers
  • Building codes requiring curbs and gutters

Strategies for overcoming these code and ordinance related barriers include performing an audit of the codes and ordinances, amending codes and ordinances, and developing design guidance for GSI that are acceptable within the bounds of existing codes and ordinances. Resources in addressing code and ordinance barriers to GSI include:

  • WI Sea Grant Tackling Barriers to Green Infrastructure: An Audit of Municipal Codes and Ordinances
  • USEPA Overcoming Barriers to Green Infrastructure

Ordinance Resources and Guidance Documents

Many resources and guidance documents exist for developing ordinances. A non-exhaustive list of these is provided in the table below.

Resources

References

  • Conservation International, 2019. ’Practical Guide to Implementing Green-Gray Infrastructure’.
  • CVC & TRCA, 2010. Credit Valley Conservation and Toronto and Region Conservation Authority, 2010. LID-SWM-Guide-v1.0_2010_1_no-appendices.pdf (sustainabletechnologies.ca)
  • FEMA, 2021. ‘Building Community Resilience with Nature-Based Solutions: A Guide for Local Communities’
  • Franke, 2016. Tom-Franke.pdf (rgvstormwater.org)
  • MNDNR, 2021. Climate trends | Minnesota DNR (state.mn.us)
  • MODNR, 2012. Integrating Green Infrastructure Into Ordinances
  • New York Times, 2020. ‘How Decades of Racist Housing Policy Left Neighborhoods Sweltering’
  • Prince George’s County Climate Action Commission, 2021. Climate Action Plan (Nov. 2021 revision)
  • NOAA, 2015. A Guide to Assessing Green Infrastructure Costs and Benefits for Flood Reduction
  • Project Drawdown, 2021. Food, Agriculture, and Land Use Solutions
  • The Nature Conservancy / AECOM, 2021, ‘Promoting Nature-Based Hazard Mitigation Through FEMA Mitigation Grants’

University of Minnesota, 2022. Sharing in the Benefits of a Greening City Toolkit

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