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EPA Tools and Resources Webinar: National Stormwater Calculator

August 23, 2017 @ 3:00 pm - 4:00 pm EDT

National Stormwater Calculator

Stormwater discharges continue to cause impairment of our Nation’s waterbodies. In order to reduce impairment, EPA has developed the National Stormwater Calculator (SWC) to help support local, state and national stormwater management objectives and regulatory efforts to reduce runoff through infiltration and retention using green infrastructure (infrastructure based on natural processes) practices as low impact development (LID) controls. The primary focus of the SWC is to inform site developers on how well they can meet a desired stormwater retention target with and without the use of green infrastructure. It can also be used by landscapers and homeowners. The SWC is a Windows-based desktop program that requires an internet connection. A mobile web application version that will be compatible with all operating systems will be released this fall.

Cost Module. An LID cost estimation module within the application allows planners and managers to evaluate LID controls based on comparison of regional and national project planning level cost estimates (capital and average annual maintenance) and predicted LID control performance. Cost estimation is accomplished based on user-identified size configuration of the LID control infrastructure and other key project and site-specific variables. This includes whether the project is being applied as part of new development or redevelopment and if there are existing site constraints.

Climate Scenarios. The SWC allows users to consider how runoff may vary based both on historical weather and potential future climate conditions. To better inform decisions, it is recommended that the user develop a range of SWC results with various assumptions about model inputs such as percent of impervious surface, soil type, sizing of green infrastructure, as well as historical weather and future climate scenarios. Please check with local authorities about whether and how use of these tools may support local stormwater management goals.

Who should attend?

State environmental and health agencies, tribes, local governments, communities, stakeholders and others interested in learning about reducing stormwater runoff.

Register for the webinar here.

If you are unable to listen through your computer speakers, please dial: 1-866-299-3188. Access Code: 202-564-6669. Please note telephone lines are muted during the webinar.

Click here for additional information and webinar recordings can be found.

Please contact Lisa Matthews (matthews.lisa@epa.gov) for more information or Amy Scheuer (scheuer.amy@epa.gov) with registration questions.


August 23, 2017
3:00 pm - 4:00 pm