Publication Summary

In 1995, Ecology completed a TMDL study (water cleanup plan) of Salmon Creek and four of its tributaries. The study found violations of Washington State water quality standards for fecal coliform bacteria, turbidity, dissolved oxygen, and temperature. In 2001, Ecology submitted a TMDL report to EPA to address fecal coliform and turbidity in the Salmon Creek watershed. Since the TMDL study, several pollution reduction actions have been implemented. This evaluation shows that fecal coliform concentrations in Salmon Creek and its tributaries have improved significantly. However, water quality criteria have not been met at some sampling stations. All of the sites met TMDL target limits for turbidity.

The Washington State Department of Ecology (Ecology) is required, under section 303(d) of the federal Clean Water Act and U.S. Environmental Protection Agency (EPA) regulations, to develop and implement Total Maximum Daily Loads (TMDLs) for impaired waters. Following TMDL implementation, data are collected to determine if the TMDL targets and water quality standards have been met.

In 1995, Ecology completed a TMDL study of Salmon Creek and four of its tributaries. The study found violations of Washington State water quality standards for fecal coliform bacteria, turbidity, dissolved oxygen, and temperature. Water quality monitoring by Clark Public Utilities from 1995 to 1999 showed that many of those violations were continuing. In 2001, Ecology submitted a TMDL report to EPA to address fecal coliform and turbidity in the Salmon Creek watershed.

The 1995 TMDL study identified percent reductions needed in fecal coliform and turbidity concentrations at four compliance sites on Salmon Creek and four of its tributaries: Cougar, Mill, Curtin, and Weaver Creeks.

Since the TMDL study, several pollution reduction actions have been implemented. These include decommissioning of high-risk, onsite sewage treatment systems; installation of riparian fencing and plantings; and completion of stormwater improvement projects.

The primary goal of this effectiveness monitoring study is to evaluate attainment of the percent reductions (load allocations) at several compliance stations identified for bacteria and turbidity concentrations and load reductions in the 2001 TMDL report.

This evaluation shows that fecal coliform concentrations in Salmon Creek and its tributaries have improved significantly since the 1995 TMDL study. However, water quality criteria have not been met at some sampling stations. All of the sites met TMDL target limits for turbidity