There are a variety of free modeling tools available to help guide you in your quest to using the Green Streets, Green Jobs, Green Towns (G3) approach to incorporate green streets and innovative stormwater management techniques in your community. Modeling tools support planning and design decisions on a range of scales from setting a green infrastructure target for an entire watershed to designing a green infrastructure practice for a particular site or location, such as a green street. Outputs that are particularly helpful include:

• runoff volume,
• runoff rate,
• pollutant loading, and
• cost.

Some models can predict the water quality and water quantity impacts of green infrastructure approaches. Start with simpler, less resource-intensive models and advance into more complex models that require more time and expertise.

Tools

1. EPA's Water Quality Scorecard - This EPA product is a tool that communities can use to collaboratively identify the barriers to green infrastructure in local codes and ordinances. The scorecard guides municipal staff through 230 policies, codes, and incentives that could be adapted to promote sustainable stormwater management. The scorecard also provides extensive references and case studies.
    
2. EPA's National Stormwater Calculator - A stormwater management model (SWMM) based desktop application that estimates the impact of land cover change and green infrastructure controls on stormwater runoff from a selected site. Estimates of runoff volume and frequency are based on local soil, topographic and climate data, and user-provided land cover and BMP data.
    
3. EPA's Stormwater Management Model (SWMM) with LID Controls - SWMM is used throughout the world for planning, analysis and design related to stormwater runoff, combined and sanitary sewers, and other drainage systems in urban areas. There are many applications for drainage systems in non-urban areas as well.  SWMM 5 has recently been extended to model the hydrologic performance of specific types of low impact development (LID) controls.  The LID controls that the user can choose include the following seven green infrastructure practices: permeable pavement, rain gardens, green roofs, street planters, rain barrels, infiltration trenches, and vegetative swales.
    
4. WERF's Using Rainwater to Grow Livable Communities Online Toolbox Exit - Water Environment Research Foundation (WERF) Online toolbox provides a variety of tools that fall into the following sections: basic principles, strategies for success, frameworks for success, communication aids, planning and development aids and stormwater BMPs.  
    
5. WERF's Stormwater BMP Interactive Model Exit- The Stormwater BMP Interactive Model is an interactive tool that allows users to observe the general stormwater runoff reductions that can be gained by applying stormwater BMPs in urban areas. While this model is intended to only be used as a demonstration and general planning tool, it can provide some baseline information for planning and exploring stormwater BMP installation options.
    
6. WERF's BMP SELECT Model Exit - SELECT is a simple planning level tool that enables a stormwater manager to examine the effectiveness of alternative scenarios for controlling stormwater pollution and the whole life cost associated with each scenario.
    
7. Watershed Resources Registry Exit - An interactive mapping tool to characterize and prioritize natural resource management opportunities using a Watershed Approach.  The objective of the Registry is to map natural resource areas that are a priority for preservation and to identify sites best-suited for ecosystem preservation and restoration.  
    
8. Center for Neighborhood Technology Green Values National Stormwater Management Calculator Exit - A tool for quickly comparing the performance, costs, and benefits of green infrastructure, or Low Impact Development (LID), to conventional stormwater practices.  The GVC is designed to take you step-by-step through a process of determining the average precipitation at your site, choosing a stormwater runoff volume reduction goal, defining the impervious areas of your site under a conventional development scheme, and then choosing from a range of green infrastructure Best Management Practices (BMPs) to find the combination that meets the necessary runoff volume reduction goal in a cost-effective way.
    
9. i-Tree Streets Exit - Focuses on the ecosystem services and structure of a municipality’s street tree population. Uses a sample or complete inventory to quantify and put a dollar value on trees’ annual environmental and aesthetic benefits.
    
10. Low Impact Development Urban Design Tools Website Exit - This site provides watershed managers with a new set of tools and techniques that can be used to meet regulatory and receiving water protection program goals for urban retrofits, re-development projects, and new development sites.

To access additional models that address stormwater runoff, cost, air quality, and energy consumption visit EPA's Green Infrastucture Modeling Tools webpage.

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