Impervious surfaces are developed and maintained by the Stormwater Services Division in order to determine ERU values for stormwater billing. The polygons are digitized using the most recent available aerial photography, as well as demolition permits, zoning changes, as-builts and customer inquiries/input. For this purpose, an impervious surface is any surface that water is unable to penetrate. These surfaces include buildings, asphalt/street, concrete/sidewalk, driveways, paths, etc.

Impervious surfaces are developed and maintained by the Stormwater Services Division in order to determine ERU values for stormwater billing. The polygons are digitized using the most recent available aerial photography, as well as demolition permits, zoning changes, as-builts and customer inquiries/input. For this purpose, an impervious surface is any surface that water is unable to penetrate. These surfaces include buildings, asphalt/street, concrete/sidewalk, driveways, paths, etc.