Natural Drainage Projects
Natural drainage systems (NDS) are an innovative alternative to traditional stormwater management systems. The pipes and ditches of traditional drainage systems carry runoff with traces of everyday contaminants such as oil, paint, fertilizer, and heavy metals directly into creeks, lakes, and Puget Sound. The speed and volume of water coming out of pipes erodes stream channels. These problems decrease water quality, disrupt marine food chains, and negatively impact wildlife habitat.
Natural drainage systems limit the negative impacts of stormwater runoff by redesigning residential streets to take advantage of plants, trees, and soils to clean runoff and manage stormwater flows. Vegetated swales, stormwater cascades, and small wetland ponds allow soils to absorb water, slowing flows and filtering out many contaminants.
- Street Edge Alternatives
- 110th Cascade Project
- Broadview Green Grid
- High Point Natural Drainage System
- Pinehurst Green Grid
- Swale on Yale
Directions to Each Site (pdf)
Most project sites are accessible by car, bus, or bicycle.
Seattle’s Natural Drainage Systems Booklet (pdf)
This illustrated booklet, published thanks to an "Innovations in Government" award from the Kennedy School of Government at Harvard University, provides a comprehensive look at Seattle's nationally acclaimed Natural Drainage Systems projects from concept development through the refinement of NDS strategies and their application to various urban settings.
Seattle Natural Drainage Systems Program Presentation (pdf)
Learn about the problems threatening our waterways and how NDS have proved an effective part of the solution.
Cost-Benefit Analysis (pdf)
NDS Plant List (pdf)
Compilation of plants used on NDS projects.
NDS Street Design Guidelines - February 2007 (pdf)