Bioretention hydrologic performance studies

Use of bioretention is widespread in the Puget Sound region and expected to increase as a preferred means for stormwater flow control and reducing pollution.

State and local governments are eager to evaluate and ensure that bioretention facilities constructed under Ecology’s Stormwater Management Manual for Western Washington attain the desired performance.

Studies underway

Two projects of a similar design are currently active to evaluate bioretention facilities built to two different design standards. 

  1. The City of Bellingham is leading the evaluation of older bioretention facilities, those built before the 2012 design standard.
  2. The City of Olympia is leading the project to evaluate facilities built to the 2012 bioretention design standard.
Both projects will assess performance of the facilities to capture, infiltrate stormwater runoff. Results will be compared to model predictions. The findings will provide feedback on design, construction, maintenance, or modeling that impact the hydrologic performance of bioretention facilities.
Pre-2012 Bioretention Hydrology Performance Study
Current Design Bioretention Hydrology Performance Study