Office of Environmental Health Hazard Assessment
Home Ecotoxicology Impervious Surface Coefficients User’s Guide and Calculator

Ecotoxicology

Impervious Surface Coefficients User’s Guide and Calculator
[12/31/10]

Follow this link to download the document Impervious Surface Coefficients User’s Guide as a pdf file

Follow this link to download the Impervious Cover Calculator as a Excel file (updated 04/07/11)

In 2008, OEHHA completed its analysis of the amount of impervious surfaces associated with California’s land uses and development patterns. These impervious surface coefficients (ISCs) reflect the percent of the area within a given land use category that is hardscape. At that time, a factsheet was prepared that summarized the different ISCs for residential and non-residential land uses. We have now completed a User’s Guide that documents the methods used to develop the coefficients, a detailed list of coefficient values, and applications of the coefficients to two common uses; stormwater runoff analysis and watershed assessment and management. In addition, an Impervious Cover Calculator is available. The Calculator supports the analysis of current and future (build out) impervious cover for any defined area of land (e.g., specific plan, watershed, etc.). We welcome questions or comments.

To inquire about our Program, contact Barbara Washburn bwashburn@oehha.ca.gov

 

 
 
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