Public Works Department

Nuts & Bolts

One of the most appealing aspects of stormwater enterprise funds is that they are designed to fit the needs of each individual municipality and can be adjusted over time to consistently meet those needs. Stormwater fees are often assessed based on the amount of impervious cover within a parcel and are determined by the municipality’s financial needs to manage the stormwater program. In accordance with the RI Stormwater Management and Utility District Act of 2002, (RIGL 45-61), all properties, except state properties, are subject to a stormwater fee, enabling the town to access the previously untapped revenue stream of tax-exempt properties. These properties, often with large rooftops and parking lots, can contribute significantly to problems with stormwater but do not typically contribute any funds towards the town’s efforts to manage stormwater.


A stormwater enterprise fund would also provide a vehicle for:

  • Consolidat­ing or coor­dinating responsibili­ties that were previ­ously dis­persed among several departments and divi­sions;
  • Generating funding that is stable, ade­quate, flexible, equitable and dedicated solely to managing stormwater;
  • Improving transparency and accountability on government spending; and
  • Developing programs that are comprehensive, cohesive and consistent year-to-year


When assessing stormwater fees, most municipalities choose to employ an Equivalent Residential Unit (ERU). An ERU represents a unit area of impervious cover and is calculated by finding the median amount of impervious cover in single-family residential parcels in town. Typically, residential parcels are used for this calculation due to their abundance and relative uniformity.


To calculate the ERU, parcels are first classified as “single-family residential,” “other residential,” “non-residential,” or “non-billable.” Non-billable parcels are either a non-parcel (such as a right of way) or exempted parcels (such as state property or parcels that reside either partially or entirely outside the town boundaries). Since Rhode Island’s GIS data for impervious cover is reasonably accurate, the median impervious cover for single-family parcels in Middletown would be used as the ERU. Total impervious cover for each parcel is then divided by the ERU (e.g. 2,500 sqft) to generate the total number of ERUs per parcel. Properties are then charged a fee per ERU, based on the rate structure established by the town.