November 21, 2002

Watch out for changes to stormwater regs

Coughlin Porter Lundeen

The state Department of Ecology is proposing new stormwater regulations that have potentially devastating impacts to the development, design and construction industries throughout Western Washington.

Much of the city of Seattle will be unaffected because stormwater runs into Puget Sound before it affects rivers, streams and protected habitats. But for the rest of the region, there’s no escape. These new regulations would reach all development sites. The effects are already being felt as developers calculate the costs of compliance.

Perhaps, before the new constraints become law, we should understand more about what they are and what they will mean to all of us in the design and construction industry.

The proposed changes are in response to the recently adopted Puget Sound Water Quality Management Plan. The impetus for these new regulations is to protect salmon habitat by protecting streambank erosion, which is directly affected by stormwater runoff.

Just like the old regulations, the new ones address the impact of development in terms of stormwater runoff, looking at the rate and quality at which it leaves a site. The impacts must be measured and the water detained and filtered or treated accordingly. The difference is that when you try to transform a sprawling suburban site into an urban village, the new regulations apply as if you were cutting down old-growth forest and paving it for the first time.

In some urban sites, much larger above-ground and underground detention facilities may be required. Detention and retention requirements could increase in size by a factor of two to four, making them too expensive for many development and improvement scenarios.

Because stormwater runoff is directly proportional to the amount of impervious surface on a site, under the new regulations any improvements or additions to the built environment would require a smaller building footprint, less surface parking and limited pedestrian corridors.

For a typical mixed-use infill project, these conditions would make redevelopment prohibitively expensive. But it doesn’t stop there. If you are planning to replace a street anywhere in the affected areas, the impact will be measured as if you were building it through old-growth forest.

That means much more construction and related costs for most streets, highways, schools and public infrastructure, as well was private development.

On the positive side, proposed regulations would leave the door open for newer approaches to stormwater management, such as biofiltration, enhanced sand filters or leaf compost. But this hardly balances the negative impacts on the economy and the disincentives for urban infill.

All municipalities with populations exceeding 10,000 in western Washington must adopt the new regulations by March 2003.

Snohomish County recently filed a lawsuit over the new regulations, arguing they are too onerous and may have a detrimental effect on its economic viability.

Design professionals, developers and land-use specialists are also concerned about the new regulations. They see them as onerous, with the potential for devastating cost effects.

Here are some of the expected impacts on site development:

  • Increased construction time and costs due to more extensive site development requirements;

  • Increased transportation improvement costs;

  • Larger, more expensive underground, surface and pond detention facilities;

  • Greater inconvenience and disruption to nearby residents and businesses due to increased site work and construction time

  • Less urban infill

So what can you do? Since cities are required to adopt the regulations (as is, or a tailored version) it will be helpful to talk with building officials. See if it is possible to get “grandfathered” under the current regulations. Design professionals and land-use specialists familiar with the new regulations should be able to advise you of potential impacts to your projects at the city and county level.

Let your elected officials know you have great concern for the economic and environmental issues of our region. We need to mitigate the effects of stormwater on the environment, but we might pursue a version of the regulations that balances economic issues in a more even-handed manner.

Read the proposed revisions to the state Department of Ecology Stormwater Management Manual for Western Washington. They can be found on the Web, with introductory and summary information, at A more in-depth explanation of the new regulations can be found at

Steve Porter is a principal at Coughlin Porter Lundeen, where he specializes in permitting requirements related to site development.

Other Stories:

Copyright ©2009 Seattle Daily Journal and DJC.COM.
Comments? Questions? Contact us.