Holden Natural Drainage Systems Project

Example of a natural drainage system project a few years after installation
Example of a natural drainage system project a few years after installation

Project description

Improving creek water quality, increasing landscaping diversity, and providing roadway and pedestrian safety improvements

More than 12 million pounds of pollution are carried into our water bodies through stormwater runoff each year. Stormwater that falls on the roofs, streets, and parking lots in your neighborhood can pick up harmful pollutants before entering Longfellow Creek, which flows into Puget Sound. The pollutants can harm fish, wildlife, and our ecosystems. The Holden Natural Drainage Systems (NDS) Project plans to build natural drainage systems, also known as roadside rain gardens or bioretention, on SW Holden Street between 16th Avenue SW and 17th Avenue SW and along the east side of 17th Avenue SW between SW Holden Street and SW Kenyon Street. The NDS will capture and treat stormwater runoff before it reaches Longfellow Creek and Puget Sound.

The NDS will be built in the space between the existing sidewalks and edge of the road. Additionally, the project will include roadway improvements such as curb bulbs, ADA ramps, and landscape plantings.

This project is likely to affect street parking. SPU knows that parking and access from the street to homes and properties are very important to community members. We carefully consider the impacts to parking in every potential project location. More detailed information will be provided as the project progresses.


The Holden NDS project area is roughly along SW Holden Street between 16th Avenue SW and 17th Avenue SW and along the east side of 17th Avenue SW between SW Holden Street and SW Kenyon Street. The map below shows the project area.


What's happening now?

The Holden NDS project is currently in the early design phase. We anticipate reaching our 30% design milestone in spring 2023 (view our early design concept (PDF)).  We are in the process of gathering feedback from the community, permitting agencies, and other impacted parties to inform the project’s design.

There will be additional in-person and online engagement opportunities as we move forward with the project’s design. Please sign up for our project mailing list  to stay up to date on these opportunities.

Community benefits

The Holden NDS Project will offer multiple benefits to local neighborhoods and ecosystems, including:

  • Improved pedestrian safety
  • Improved roadway elements
  • Increased landscaping diversity
  • Improved stormwater/drainage water quality
  • Healthier creek ecosystems

How does SPU select locations for building NDS?

SPU selects project locations by working with other city departments to identify locations where there is a need for addressing drainage issues and other community needs. The final project location will depend on other factors, such as:

  • Regulatory requirements
  • How much water can be treated
  • Location of existing underground utilities
  • Existing soil conditions
  • Width of the public right-of-way
  • Presence of driveways
  • Availability of off-street parking
  • Potential impacts to mature trees
  • Location of nearby steep slopes
  • Community input
  • Cost of project construction and long-term operation and maintenance

Community engagement

Community feedback, alongside technical evaluations, will be important to this project during each phase. The project team will work with community members to understand important issues in the neighborhood and to identify feasible locations for natural drainage systems. Community members will be able to share their feedback through a variety of online and in-person activities.

During the early stages of the project’s design, we will be conducting outreach to residents and businesses in the immediate project area. We will expand our outreach efforts to adjacent areas as we move forward in the process. Outreach will be ongoing through all phases of the project—planning, design, and construction.

If you are interested in learning more about the project and upcoming community engagement opportunities, please sign up to receive project email updates.

Planning 2022

Design 2023 -2024

Construction 2024 - 2025

This preliminary schedule will be updated as the project progresses.
Holden NDS project timeline

Natural drainage systems slow stormwater and filter out pollutants before they can harm our creeks and other waterways. Keeping pollutants out of our water is important for aquatic life and people. SPU is planning to build NDS in the Longfellow Creek watershed to improve water quality in the creek and Puget Sound.

If you are interested in learning more about how stormwater harms our ecosystems, watch this video produced by the Nature Conservancy, which highlights Longfellow Creek.

Building a natural drainage system in the Longfellow Creek basin is part of the Plan to Protect Seattle’s Waterways. SPU used to call these "roadside rain gardens" but now calls them "natural drainage systems" or "NDS." To learn more about the Holden Natural Drainage Systems Project, please view this presentation from the Highland Park Action Coalition’s (HPAC) October 2022 meeting. 

NDS helps restore functions of the land to natural condition.

Public Utilities

Andrew Lee, General Manager and CEO
Address: 700 5th Avenue, Suite 4900, Seattle, WA, 98104
Mailing Address: PO Box 34018, Seattle, WA, 98124-5177
Phone: (206) 684-3000

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Seattle Public Utilities (SPU) is comprised of three major direct-service providing utilities: the Water Utility, the Drainage and Wastewater Utility, and the Solid Waste Utility.