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Project description
May Creek tributary 291A discharges to the May Creek mainstem in the southeast quarter of Section 2, Township 23, Range 5 East, Willamette Meridian, in King County, Washington. Tributary 291A flows about 1.25 miles northerly within the May Creek basin from Cemetery Pond to the May Creek mainstem. See location map below.

May Creek was selected for stormwater retrofit enhancements because it has a high score on Ecology’s Watershed Integrity Index and ranked high on the County’s list of Small Basins for Retrofit. Additionally, May Creek is polluted by bacteria, mercury, and other metals as assessed by Ecology. Also, eroded sediments negatively impact water quality in the May Creek basin and aggrade the mainstem channel, contributing to farms and pastures flooding. 

A subbasin of the May Creek basin, tributary 291A, was selected for this work because of its size and its degree of development–six hundred acres two-thirds developed. The size of this subbasin may allow it be retrofitted more readily than the entire May Creek basin could be. This scale will allow for more rapid demonstration of the effectiveness of retrofitting.

This review for stormwater retrofit opportunities in May Creek Tributary 291A resulted in the identification of Cemetery Pond as a preferred project site. The May Creek Basin Plan (2001) recommends enhancing and restoring the wetland by cleaning up existing trash piles, replanting native vegetation and restoring filled wetland areas. The May Creek Basin Action Plan and its recommendations were developed in collaboration with, and with support from: the King County executive and council; the City of Renton mayor, city council and public works department; Newcastle City Council and staff; the May Creek Citizens Advisory Committee; the Community Alliance to Reach out and Engage (CARE); the Stewardship of Wetland Areas by Neighbors (SWAN), and the Four Creeks Unincorporated Area Council.


May Creek Tributary 291A Small Stream Basin Retrofit Project Location Map (730 Kb pdf)

Project goal
The goal of the project is to continue planning and design of a small basin stormwater retrofit with multi-benefit restoration of Cemetery Pond which enhances stormwater management in May Creek Trib291A.

Project activities

  • 2018-2020:
    • King County purchased five parcels voluntarily sold by landowners from within the project site.
    • Ecology Stormwater Grant: WQC-2018-KCWLRD-00040 was leveraged to:
      • Conduct a Wetland Delineation & Categorization Report of Cemetery Pond; and
      • Develop conceptual designs of the wetland restoration of Cemetery Pond.
  • 2020-2024: Develop a grant application for Washington State Department of Ecology Non-Point Source Funding, which would support:
    • Continuing to purchase parcels from willing landowners within the project site; and
    • Advance the conceptual Design to a final design package.
  • TBD: Funding project implementation once the final design is complete.

For more information about the Small Stream Basin Retrofit Program, please contact Matthew (Matt) McNair, Project Manager, WLR Capital Services Unit.