On Aug. 23, 2017 from 3 to 4 p.m. EDT, the U.S. Environmental Protection Agency (EPA) will discuss the National Stormwater Calculator (SWC) in a webinar. EPA developed the SWC to work toward local, state, and national stormwater management objectives. It also will support regulatory efforts to reduce runoff through infiltration and retention using green infrastructure, which manages stormwater by mimicking natural processes.

The primary focus of the SWC is to help site developers understand how well they can meet desired stormwater retention targets with and without the use of green infrastructure. It also can 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

A low-impact development (LID) cost-estimation module within the application enables planners to evaluate LID controls based on comparison of regional and national-level project capital and maintenance cost estimates and predicted LID control performance. Cost estimation operates based on user-identified size configuration of the LID control infrastructure and other key project and site-specific variables. This includes whether the project in question is part of a new development or a re-development, and if there are existing site constraints.

Climate scenarios

The SWC enables users to consider how runoff may vary based on both historical weather and future climate predictions. To better inform decisions, EPA recommends 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.

To register

This webinar is intended for state environmental and health agencies, tribes, local governments, communities, stakeholders and others interested in curbing stormwater runoff.

To join the webinar, please register online at http://epawebconferencing.acms.com/swcevent/event/registration.html.

If you are unable to listen through your computer speakers, dial: 1-866-299-3188. Access Code: 202-564-6669. Please note telephone lines are muted during the webinar. Additional information and webinar recordings can be found at https://www.epa.gov/research/epa-tools-and-resources-webinar-series.