Low Impact Development: Managing the Rain

When rain falls onto Oregon’s streets, sidewalks, parking lots and rooftops, it picks up pollutants in its path, gathering volume and speed until a storm drain pipes it underground or into a stream. This stormwater runoff causes water pollution, flooding, stream bank erosion, depleted groundwater, and habitat loss for fish and wildlife.

Using plants and soil to capture and filter stormwater runoff and allows the cleaned water to recharge our groundwater supplies, the way it does in nature. Managing stormwater this way is called low-impact development (LID). These development practices that reduce stormwater runoff by preserving existing natural landscape features and installing small-scale stormwater technologies that mimic the way rainfall distributes in nature. One example of an LID practice is a rain garden, which helps slow, capture, filter, and infiltrate stormwater that runs off of impervious surfaces.

OEC has worked with our partners to develop Low Impact Development in Western Oregon: A Practical Guide for Watershed Health, a step by step guide that cities and counties throughout Western Oregon can use to use to reduce stormwater runoff, prevent flooding, and improve the health of our rivers, lakes and streams. Involvement from Oregon DEQ helped ensure that this resource for our communities meets regulatory requirements. To read the LID manual, please click here.

The LID manual gives communities guidance in designing, constructing and maintaining greener storm water facilities. This Implementation guidance for planning, design, construction, and maintenance of post-construction low-impact practices is both:

  • Holistic: Includes structural (i.e., porous pavements and rain gardens) and non-structural (i.e.. tree planting, minimizing land disturbance) practices that protect water quality and mimic the flow of water in the natural landscape. The guide focuses on low-impact and green infrastructure, but is not an all-purpose storm water manual.
  • Customizable: Local jurisdictions can easily adapt the manual to make it their own by plugging in the appropriate design storm for their climate and geology and/or selecting which practices are most suitable for them.

With help from this guide, cities and counties across western Oregon will:

  • Save time and money: Developing a manual template that multiple jurisdictions can use will eliminate inefficiencies and save costs incurred when each city or county attempts to develop their own manual from scratch. The manual will make it easier for communities to implement LID successfully and meet stormwater permit regulations and TMDL requirements.
  • Eliminates one-size-fits-all solutions: Designed for small and mid-sized cities, this guide eliminates problems caused when jurisdictions simply refer to the City of Portland manual, which may be inappropriate for their climate or geology and too complex for their needs.

Advisory Committee

In summer 2014, OEC formed an interdisciplinary advisory committee to review the draft manual. The guide was then tested on four development projects and adjusted as necessary. We also provided workshops to help communities adopt the manual.

See who is on the technical advisory committee. 


Thank you to the following governments and organizations that have committed financial support to make this project possible.

  • City of Central Point
  • City of Coburg
  • City of Coos Bay
  • City of Cottage Grove
  • City of Keizer
  • City of Medford
  • CH2M Hill
  • Green Girl Land Development Solutions LLC
  • Oregon Association of Clean Water Agencies
  • Oregon Department of Environmental Quality
  • Oregon Department of Forestry
  • Robin Kirschbaum
  • Rogue Valley Sewer Services
  • City of Veneta

For more info

Contact Colin Price: colinp@oeconline.org

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