In most user-pays models, there are various levels of runoff, and the fee is calculated based on factors such as – the size of the property, the ratio of impervious surface, and the type of property. For example, models range from a flat fee to small through to the imperviouness of a property. Residential lots typically pay far less than industrial or commercial ones due to lower amounts of imperviousness and lower pollutant loads.
The less you pave, the more you save.
Some utility charge systems have been implemented that model a property’s impervious area using satellite imagery to calculate relative fees. These different approaches have different cost-benefits – for example, calculating the impervious area of each property will lead to more accurate charges generating more revenue, but also require higher amounts of overheads and upkeep of local property records. A bonus is significant job creation in maintenance and the need to run stormwater as its own department.