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Soos Creek watershed fecal coliform TMDL

We are developing water quality improvement projects, also known as Total Maximum Daily Load (TMDL) projects to address fecal coliform bacteria issues in the Soos Creek basin.

Along with our partners on this project, we will develop a water quality improvement report that addresses water quality standards in the Soos Creek watershed. It will contain recommendations from a TMDL study on the Soos Creek watershed and an implementation strategy. We will determine what needs to be done and who will carry out the recommendations so that the level of fecal coliform will meet state water quality standards.

Water quality issues

Soos Creek watershed drains about 70 square miles of land area and includes portions of King County and the cities of Auburn, Black Diamond, Covington, Kent, Maple Valley, and Renton. Major streams draining to Big Soos Creek include Soosette, Jenkins, Covington, and Little Soos Creeks. Land use in the study area varies from urban and residential, commercial, some industrial, commercial forestry, and small scale agricultural land uses.

Parts of the Soos Creek stream system have too much fecal coliform bacteria in the water. Several salmon species use these streams as important migration corridors to get to spawning and rearing areas. These species include:

  • Puget Sound Chinook
  • bull trout
  • coho
  • chum
  • pink
  • sockeye
  • kokanee
  • steelhead/rainbow
  • cutthroat trout

The 2014 Water Quality Assessment lists Soos Basin stream segments as not meeting water quality standards for fecal coliform in stream segments, including Big Soos, Little Soos, Covington, Soosette, and Little Soosette creeks.

What we have done

In coordination with the Soos Multiparameter TMDL, in 2012 we initiated an effort to control fecal coliform in the Soos Creek system.

Status of the projects

As the TMDL study progresses we will better identify the pollution problems and specify how much pollution needs to be reduced to achieve clean water. Throughout the TMDL study, we will work closely with the local community to prepare an implementation plan that details the specific actions needed to improve water quality in the basin. The plan will describe management roles, activities, and schedules for partners.

We will support the existing good work done by local partners and the public in new and ongoing projects, including those for proper animal waste handling, onsite septic system and management, and riparian protection projects. Bacteria management and streamside projects may be initiated through grants or using current and proposed city and county critical area ordinances and Shoreline Master Programs, which encourage preservation and restoration of riparian vegetation.

Soos Creek TMDL projects timeline

This project is being conducted separately but parallel to the Soos Multiparameter TMDL for water temperature, dissolved oxygen, and bioassessment. This TMDL will track and coordinate with the Soos multiparameter project. Timeline information for both projects can be found there.

What we all can do

King County Department of Natural Resources, the Soos basin municipalities, King County Conservation District, and local watershed groups have ongoing proper waste management and stream restoration projects, and the TMDL improvement report and plan, which is under development, will provide a basis for additional work.

Local partners involved in this effort include:

  • King County Conservation District
  • Muckleshoot Indian Tribe
  • King County
  • Cities of Auburn, Black Diamond, Covington, Kent, Maple Valley, and Renton
  • Implementation groups, such as Green River Coalition, Midsound Fisheries Enhancement Group
  • Friends of Soos Creek
  • Washington Department of Transportation
  • Water purveyors such as Seattle Public Utilities, Covington Water, and King County Water District #111
  • Watershed residents
  • Local businesses

Citizens can practice proper waste disposal and other nutrient reduction strategies. These may include:

  • Reducing lawn irrigation and fertilizer use
  • Ensuring a properly functioning on-site sewage system
  • Livestock exclusion and proper pet waste disposal
  • Planting and maintaining trees and vegetation along streams. This buffers streams from waste and nutrient runoff

For more information, see Washington Waters — Ours to Protect.

Why this matters

Fecal coliform is a type of “bacteria” common in human and animal waste. It indicates that sewage or manure is entering a water body. Bacteria can get into waters from untreated or partially treated discharges from wastewater treatment plants, from improperly functioning septic systems, and from livestock, pets, and wildlife.