New Method for Determining Impervious Areas Saves Time and MoneyStatus: CompleteReport Date: 07/28/2015 Summary: Knowing the effective impervious area (the impervious area directly connected to the storm sewer system) is critical for more accurate stormwater modeling. This report provides a practical method to determine EIA using readily available data rather other more time-consuming and expensive methods. The new method uses existing geographic information system data and Natural Resources Conservation Service data, and primarily relies on curve number, which is a parameter used to determine runoff that integrates soil type, infiltrations rates, land cover and precipitation data. Final Deliverables: Report #2015-41 Research Summary Related Materials: Related Research: