Paired watershed retrofit & restoration study

The City of Redmond is the lead agency on this multi-year complete watershed-scale stormwater retrofit effectiveness study.

There are seven watersheds in this study design:

  • Three application watersheds: Evans, Monticello, and Tosh
  • Two reference watersheds: Colin and Seidel
  • Two control watersheds: Country and Tyler's

Application watersheds will undergo large-scale retrofits to bring the watershed into current Washington stormwater management standards. Control watersheds will progress at a normal timeline of development. Reference watersheds will not develop as they are in relatively protected environments.

All watersheds included in the study are located in and around Redmond. This project will monitor the streams draining these watersheds for various hydrologic, chemical physical habitat, and biological indicators.

Study questions

  • How effective are watershed-scale rehabilitation efforts at improving conditions for small stream receiving waters?

Scope of work

This effectiveness study will span 10 years (2015-2025), currently monitoring is funded through March 2023. Due to the extended timeline on this project, only the most important tasks and deliverables are summarized. The study’s sampling quality assurance project plan provides information on the sites and study design. The sub-project effectiveness studies for Pond Retrofit and Street Sweeping are described under addendums or separate monitoring plans than the original QAPP.

Planning and preparation deliverables:

Study findings

Water Year Final Reports and Trend Reports:

The report's appendices contain multiple incremental deliverables such as the hydrologic summary, King County’s data quality assurance review, water quality summary, and sediment quality summary.