Stormwater FAQs

Stormwater FAQs

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1. What is stormwater? Why is it important?
Stormwater starts as just regular rainwater, but as it runs off of roofs, through yards, down driveways, or any other impervious surface (see question #2 for more on what impervious surface means), the water can pick up pollutants like dirt, trash, animal waste, oil, gas, fertilizers, pesticides, metals, and other materials in its path.

Stormwater flows untreated directly into our streams, lakes, and rivers; the same bodies of water we use for swimming, boating, fishing, and shellfish harvesting.

When it rains, a certain amount of rainfall will naturally soak into the ground, especially if it's in an area with lots of vegetation or trees. But as an area develops, less rainfall soaks into the ground and more becomes stormwater, which means higher flows into storm drains and waterways. Higher stormwater runoff amounts mean greater chances of flooding, property damage, soil and stream erosion, and impacts on water quality and stream health.

2. What is impervious area? Why do we use it in determining stormwater charges?
Impervious area refers to surfaces that minimize the ability of rainfall to soak into the ground, causing runoff (ex: roofs, garages, carports, storage sheds, sidewalks, roads, parking lots, patios, etc.).  The runoff can cause flooding and drainage issues.

When billing for stormwater, we consider the amount of impervious area on each property. The stormwater fee reflects the amount of stormwater runoff that each individual property contributes to the community’s overall stormwater runoff.

The more impervious surface area a property has, the greater amount of stormwater that runs into our conveyance system and streams, thus the greater demand on the drainage infrastructure.

3. What is an Equivalent Service Unit (ESU) and how was it developed?
An Equivalent Service Unit (ESU) is the unit of measurement we’re proposing to use to bill the stormwater fee.

The ESU was developed by reviewing the impervious surface area of residential properties located in the City of Shelton. Each property was measured, and a median (average) impervious surface area was determined to be 2,900 square feet. 2,900 impervious square feet equals one ESU.

4. Why are we changing the stormwater rate structure?
Our current rate structure has been in place since 2005, and the fees have been the same since 2009. The revenue generated by the current fees is not enough to pay for:

  • Necessary operations
  • Maintenance
  • Upgrade projects
  • New state regulatory requirements

Additionally, the current rate structure is based on tiers of impervious surface area and doesn’t equitably charge each customer. Here’s an example: a customer that falls within the first tier (0-5,000 impervious square feet or isf) pays one rate, the next tier (5,001-10,000 isf) pays a higher rate, then 10,001-25,000 isf, and so on, with a cap at 55,000 impervious square feet.

This is a problem because many customers at the tier edges pay a significantly higher fee for just a few more square feet of impervious surface. Also, capping the amount of impervious square feet at 55,000 means that a customer with 600,000 impervious square feet would pay the same amount as a customer with 55,000 impervious square feet.

We recognized these inequities and commissioned a rate study, which determined the best route to remedy the issue and equitably balance the rate structure would be to move to an ESU (equivalent service unit) rate structure.

5. What does the stormwater fee pay for?
The stormwater fee ensures that we’re meeting federal and state water quality mandates, protecting and improving our water quality, and funding upgrades and improvements to stormwater infrastructure to alleviate flooding throughout Shelton.

Specifically, the stormwater fee pays for activities such as:

  • Monitoring water quality of local waterways to control potential discharge of pollutants
  • Identifying and eliminating improper connections that illegally dump waste, instead of stormwater, directly into our rivers and streams
  • Developing plans to properly address stormwater runoff throughout the existing stormwater system
  • Performing regular system maintenance and state permit compliance reporting
  • Upgrading, repairing, and replacing the existing stormwater infrastructure to reduce flooding and pollution
  • Removing stormwater from the sanitary sewer system (also known as inflow & infiltration)
  • Providing public outreach and education opportunities