King County logo

Sammamish River Water and Sediment Quality Assessment - Sampling and Analysis Plan

King County plans to conduct a sediment and water quality assessment of the Sammamish River.  Sediment, surface water, and benthic community samples will be collected for analyses during the summer/early fall of 2001 and 2003.  Additionally, surface water samples will be collected in 2002 to broadly characterize potential changes between years.  King County may continue the sampling program into 2004 and beyond depending on the results of a comprehensive review of Sammamish River monitoring data and/or specific data needs.  This Sampling and Analysis Plan (SAP) describes the planned scope of work for 2001-2003, including field sampling procedures, and laboratory analytical requirements for the project.  A SAP addendum will be prepared as necessary to document the scope of work for 2004 and beyond.

Currently, little or no concentration data exist for metals, pesticides, and/or organic compounds that may be present in the water column or sediments of the Sammamish River.  It is unknown if water or sediment quality conditions limit reproduction and/or survival of aquatic life, especially endangered salmon, which reside in or use the river as a migration corridor to reach rearing or spawning areas (e.g., Bear Creek, Issaquah Creek).  A variety of land uses currently exist in the river corridor that likely contribute to the overall contaminant loading to the river (e.g., agriculture, suburban, light industrial).  Recently, research conducted by NMFS (Scholz et al. 2000) suggests short-term exposure to low levels (i.e., 0.1 ppb) of diazinon (one of many pesticides used in the basin) can interfere with the homing behavior of endangered Chinook.  Diazinon concentrations within the Lake Washington watershed tributaries have been found to exceed 0.1 ppb (USGS 1999, King County 2002a).  Based on the current land use activities in the Sammamish basin (e.g., suburban residential, agriculture, golf courses), it is likely diazinon along with other pesticides and contaminants are present in the river.  It is unknown, however, if aquatic life, especially endangered salmon, are exposed to harmful levels of these compounds that result from non-point source runoff in the basin.

Before restoration, salmon recovery, and/or other efforts (e.g., water reuse implementation) within the Sammamish Corridor can be designed and implemented, it is critical to develop a thorough scientific understanding of the current chemical and biological conditions of the river.  This project will provide some of the information necessary for decision-makers to better identify problem areas and assist with management decisions regarding water reuse, the Endangered Species Act issues, and watershed management.  These data will also be used in a number of modeling applications as part of the Sammamish and Washington Assessment and Modeling Project (SWAMP).  The models will be able to simulate potential conditions associated with various reuse options and compare predicted sediment and water quality under these options to baseline conditions.

Finally, the data collected in this sampling program will be used to develop a long-term monitoring plan for Sammamish River.  Various King County sampling programs have generated chemical and biological data for Sammamish River over multiple years.  All of the data, including that generated from the activities described in this SAP, will be evaluated to assess the specific needs for long-term monitoring in the Sammamish River.

View the report

    Sammamish River Water and Sediment Quality Assessment (1155.00 KB)

You can download a free copy of Adobe© Acrobat© Reader