In creating the Utility, the City declared its intention to establish and impose just and equitable charges on storm water drainage utility users. These charges (user fees) are used to pay the costs directly associated with operating and maintaining the Utility.
The main factor in contributing storm water runoff from a particular property is the amount of impervious surface area on that property. Impervious surfaces are those surfaces which prevent water from soaking into the ground, such as a building roof, parking lot (compacted dirt and gravel lots included), driveway, sidewalk, etc.
Based on the information obtained by the City Engineers, the typical residential property contains 2,530 square feet (square feet) of impervious surface area. The units to be used in determining the appropriate user fee is the ERU (Equivalent Residential Unit). One ERU is 2,530 square feet of impervious surface area. Therefore, all single-family residential properties have, by definition, an ERU rating of 1.0 ERU.