rain garden next to a Puget Sound Beach

Assessing and Monitoring Rain Gardens

Rain garden and bioretention assessment protocol

Volunteers assess rain garden function in Port Townsend, WA.
Volunteers assess rain garden function in Port Townsend, WA

This easy-to-use field protocol is intended to help interested citizens and local staff gather the necessary information to assess the performance of bioretention facilities and rain gardens. The information can be used to correct immediate problems and by stormwater system managers to inform long term maintenance and design considerations.

This assessment protocol was developed in partnership with the City of Puyallup, Stewardship Partners, the Washington Stormwater Center and WSU Extension. In addition, more than 90 dedicated volunteers participated in the training and conducted the field work necessary for the development and refinement of this assessment protocol. We could not have done it without them. Thank you!

Here are materials created for your use.


Video explains how to do a rain garden assessment.

Step by step instructions for completing a rain garden functionality assessment.

Handy in-the-field-handouts of visual assessment resources.

In-depth webinar slide presentation about this assessment program.

Data Forms & Database

Use this template form to complete a rain garden functional assessment.

WSU website for completing a rain garden functional assessment. (*Note: Please establish and use “Group Code” when inputting data into the database)

This template can be used if there are multiple rain gardens to assess at your site.

WSU website database for tracking rain garden functional assessments. This is a downloadable .csv file, sortable by “Group Code.”

Results and Resources

Summary of results from using this rain garden functionality assessment system.

Overview of the project presented at Municon Conference 2019.

Landowner survey in conjunction with rain garden functionality assessments.

Using the results from this project, a proposal for scaling up this assessment program.

To view all the materials and learn more about the project, please visit the Washington State Department of Ecology’s Stormwater Action Monitoring (SAM) website.

This project was funded by the Stormwater Action Monitoring (SAM) program, which is a collaborative, regional stormwater monitoring program that is funded by more than 90 Western Washington cities and counties, the ports of Seattle and Tacoma, and the Washington State Department of Transportation. SAM’s goal is to improve stormwater management to reduce pollution, improve water quality, and reduce flooding. We do this by measuring stormwater impacts on the environment and evaluating the effectiveness of stormwater management actions.

Stormwater Action Monitoring (SAM) logo
City of Puyallup Logo
Stewardship Partners logo