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Stormwater System

Residents enjoy flood prevention and healthy local waterways thanks to the City of Hillsboro Public Works Department’s Surface Water Management (SWM) Program.

The SWM Program includes the Stormwater System. 

Benefits of the Stormwater System: 

  • Prevents flooding and damage to property
  • Helps the ecosystem reclaim water
  • Enhances water quality
  • Increases the health of local waterways.


The Stormwater System collects, moves, and treats stormwater – or rain and snowmelt – before it is released into local waterways. 

A street storm drain collects rain near the curb

The system consists of more than: 

  • 8,600 catch basins
  • 6,300 manholes
  • 270 miles of underground storm pipes
  • 250 miles open channels
  • 325 water quality facilities
  • 490 outfalls

The Stormwater System is separate from the Sanitary Sewer System, which carries wastewater from sinks, showers, and toilets away from neighborhoods to wastewater treatment facilities.

Although both are out-of-sight, the health and sanitation of our City and local waterways depend on these two separate underground systems.


The Public Works Department is responsible for managing, inspecting, and cleaning the public Stormwater System. 

Property owners are responsible for the storm lines that connect homes and business to the public system. 


A graphic representation of the City's Stormwater and Sanitary Sewer Systems.The stormwater conveyance system includes four parts:

  1. Stormwater flows over impervious surfaces, collecting debris, sediment, and pollution. Stormwater empties into a local waterway or enters the Stormwater System through catch basins, open channels, and private laterals.
  2. After entering the system, stormwater moves through a network of underground storm pipes, manholes, and open channels to water quality facilities.
  3. Water quality facilities treat stormwater by removing pollutants and provide temporary storage prior to being released to local waterways.
  4. Outfalls represent the end of the system and release stormwater into local waterways.

View a graphic representation of the City's Stormwater and Sanitary Sewer Systems


A fixed charge and a Local Service Fee (LSF), both of which are included on customers’ City utility bill, fund the SWM services provided to the Hillsboro community. 

  • Clean Water Services charges a fixed regional charge to fund capital efforts such as street sweepers and Stormwater System operation and maintenance.
  • The City established the LSF in 2015 to raise revenue needed for continued investment in the repair and replacement of aging stormwater infrastructure (deferred maintenance). 

The LSF rate was set at and currently is $1 a month per Equivalent Service Unit (ESU). ESU is the size of the impervious surface area on a property. One ESU equals 2,640 square feet of impervious surface. Most single-family residential customers are billed a flat rate of $1, or one ESU. All other properties pay based on their measured impervious area.

The City is considering increasing the monthly LSF. Visit the Local Service Fee page to learn more.

A map of the projects funded by the Local Service Fee from 2015 to 2020.Projects

Since January 1, 2015, the LSF fee has funded several high priority projects to improve the function of the existing Stormwater System.

Completed projects include:

Additional projects – currently in design or construction - are also funded in part or completely by the LSF, including:

  • Water quality facility and outfall rehabilitation projects
  • Increased system capacity projects
  • Stormwater Master Plan development

View a map of projects funded by the Local Service Fee from 2015 to 2020