Hydromodification: What to Expect in Washington County

Clean Water Services Planning and Development Manager Damon Reische presented on recently adopted revisions to the design and construction standards for stormwater management in Washington County, which recently went into effect on April 22, 2019.
 
Hydromodification occurs when development changes previously pervious surfaces to impervious, resulting in more water entering streams through conveyance pipes at a faster rate. This can lead to increased flooding, impacts on water quality, soil erosion, and effects on downstream fisheries. The design and construction standards cover sanitation and storm conveyance, stormwater management, erosion control, pump stations, and vegetative corridors. Damon gave an overview of the strategy to address impacts of hydromodification, stormwater management categories, and fee-in-lieu options for projects. For more information on the home building industry’s efforts to ensure the new standards to not unduly increase housing costs, please contact Ezra Hammer at ezrah@hbapdx.org.

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