Surface Water Management

This division continuously works toward maintaining and improving the quality of our natural waterways as well as addressing flooding concerns. When rain flows across impervious surfaces such as rooftops, pavement and sidewalks, it picks up sediment and pollutants before it flows into our stormwater conveyance system and into our natural waterways. Stormwater can cause flooding, impact water quality and affect our streets. The Surface Water Management division manages stormwater runoff to prevent damage to people and property as well as to maintain and enhance our natural environment.

Efforts of the division include: surface water development review and inspections, maintaining public stormwater systems, inspecting privately maintained stormwater systems, monitoring our natural waterways, and providing stormwater education and outreach programs.

Newcastle has over 3,000 catch basins, 3,500 pipe sections, and over 80 stormwater facilities (detention ponds, tanks, and vaults). Our natural waterways include Lake Boren, China Creek, Boren Creek, May Creek, Newport Hills Creek, Gypsy Creek, and wetlands. To help protect our natural waterways and their ecosystems, it is essential that our stormwater systems are maintained regularly.

What is Stormwater?
Stormwater becomes polluted when it travels over our yards, roads and sidewalks. Stormwater flows to storm drains and ditches, which empty directly into our lakes and streams often without treatment.

StormwaterWhen stormwater picks up sediment, fertilizer, pesticides, oil, soap, and bacteria from pet waste, water becomes polluted. Stormwater is managed to ensure the health and safety of our citizens, our natural waterways, and wildlife.

Comprehensive Surface Water Management Plan
This is a 5-year stormwater master plan that sets priorities for stormwater capital improvement projects. The plan makes recommendations based on the health of our natural waterways, maintenance requirements, and hydrologic and hydraulic models of our stormwater system.

Comprehensive Surface Water Management Plan (2010)  
2017 Comprehensive Surface Water Management Plan Update (Updated 2018)

Stormwater NPDES Permit

The City of Newcastle is required to have a National Pollution Discharge Elimination System (NPDES) Phase II Municipal Stormwater Permit under the federal Clean Water Act. In Washington State, the NPDES stormwater permits are regulated by the Department of Ecology (Ecology). Permit compliance includes mapping, inspections, maintenance, monitoring, and public outreach.

As part of our NPDES permit, we are required to prepare and submit an Annual Report to Ecology every year, which summarizes the City’s efforts to comply with permit requirements.

2015 Annual Report (PDF)
2016 Annual Report (PDF)
2017 Annual Report (PDF)
2018 Annual Report (PDF)
2019 Annual Report (PDF)
2020 Annual Report (PDF)
2021 Annual Report (PDF)

Stormwater Managem
ent Program Plan
The Stormwater Management Program Plan (SWMP) is updated every year, and provides information regarding Newcastle’s NPDES permit compliance. A SWMP is a set of actions and activities comprising of the following five components:

— Public Education and Outreach
— Public Involvement and Participation
— Illicit Discharge Detection and Elimination (IDDE)
— Controlling Runoff from New Development, Redevelopment and Construction Sites
— Pollution Prevention and Operation and Maintenance for Municipal Operations

2016 Stormwater Management Program Plan (PDF)
2017 Stormwater Management Program Plan (PDF)
2018 Stormwater Management Program Plan (PDF)
2019 Stormwater Management Program Plan (PDF)
2020 Stormwater Management Program Plan (PDF)
2021 Stormwater Management Program Plan (PDF)

Surface Water Management Fees
Newcastle’s Surface Water Management fees are assessed once a year and are part of property taxes. The fees are a flat rate for single-family residential property owners. For multi-family residential and commercial property owners, the stormwater fees are based on the percentage of impervious surface on the property.

Our Natural Waterways and Drainage Basins
Newcastle lies within portions of three larger watersheds, Coal Creek watershed, East Lake WasLake Borenhington watershed, and May Creek watershed. Within each watershed, there are smaller drainage basins. More information about our drainage basins is available in section 3.2 of our Comprehensive Surface Water Management Plan. Natural waterways within Newcastle include Lake Boren, China Creek, Boren Creek, Newport Hills Creek, Gypsy Creek, May Creek, and wetlands.

Water Quality Monitoring Data
Lake Boren is recognized as a valuable environmental and recreational asset of the community of Newcastle. The City partners with King County to collect and analyze water quality data to learn about the current hydrologic conditions and monitor changes in the lake. This data is helpful to make management decisions to improve and maintain the aquatic ecosystem.

Lake Boren Water Quality Data (King County Website)

To learn more about Lake Boren and previous year’s data, please visit the King County Lake Stewardship Program here.

Additional Resources
Construction stormwater permit - Washington State Department of Ecology

Notice of Intent (NOI) for Coverage under a National Pollutant Discharge Elimination System (NPDES) Municipal Stormwater General Permit

SecureAccess Washington

Industrial stormwater permit - Washington State Department of Ecology


If you need to report a hazardous spill or urgent matter 24 hours a day, 7 days a week, call 206-296-3311.

To report a non-hazardous spill during regular business hours
(Monday-Friday, 8 a.m. to 5 p.m.)
Call 425-649-4444

On evenings and weekends call 206-296-3311

For drainage concerns or other water quality concerns, submit a request using SeeClickFix at

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