Ambient Stream Biological Monitoring Project

Ambient monitoring site, Cook Cr nr mouth



The Federal Clean Water Act (Section 101) mandates the development of water management programs that evaluate, restore, and maintain the chemical, physical, and biological integrity of the nation’s waters (U.S. EPA 1990).   Traditional measurements of chemical and physical components for rivers and streams do not provide sufficient information to detect or resolve all surface water problems.   Biological evaluation of surface waters provides a broader approach because degradation of sensitive ecosystem processes is more frequently identified. Biological assessments supplement chemical evaluation by:

Ecology collects biological information from rivers and streams throughout the state. The long-term monitoring project was established in 1993 to explore spatial patterns and identify temporal trends in benthic macroinvertebrate communities. Gradually, the project has developed a large base of information that describes biological characteristics of reference and degraded conditions.   Reference conditions are found in streams with little or no human impact.

This project focuses on determining methods for reliably interpreting biological and associated habitat data.   This is accomplished by delineating regions of relatively homogenous natural biological communities in the state and comparing streams within each region along a gradient of impairment.   Application of biological expectations are also applied to broad geographic areas defined by existing regional descriptors and by landscape variables such as elevation, climate zones, or topography.   Identification of factors in streams that are directly correlated with biological attributes can be useful in tracing the sources of impacts.   Tools for interpreting data are developed by using known stream conditions (naturally and highly degraded) and calibrating the responses of each biometric or community diversity measure to the known condition.

Biological information is used to evaluate stream impacts from point- and non-point sources of pollution.  Integrating this information with physical and chemical characterization of a stream segment provides an effective way for diagnosing sources of degradation.


Long-term biological monitoring of rivers and streams in Washington attempts to incorporate biological and associated habitat information into the regulation and conservation of environmental resources.   Past and current development of biological criteria to detect human-induced impacts in streams is an essential step in this process. Evaluation of biological criteria follows the acquisition of new information, which is collected on an annual basis.  Therefore, the objectives and applications of information from this monitoring project are as follows:

History of the Project

Following preliminary surveys in 1993, a consistent strategy for collection of aquatic invertebrates (benthic macroinvertebrates) was developed by 1994 (see Ecology Pub #94-113). A revised protocol document was re-issued in 2001 (Ecology Pub #01-03-028). The monitoring project design focuses on invertebrate community similarity at a regional scale and then further evaluation of human impacts at the local scale.

Monitoring Strategy

Core Site Monitoring

Beginning in 2002, ten core reference sites are to be monitored annually and dispersed among the regions. The purpose of this monitoring is to track the influence of climate cycles and describe variability patterns inherent in biological communities throughout the state.

Core reference sites:

  1. Austin Creek
  2. Chuckanut Creek
  3. Diobsud Creek
  4. Seabeck Creek
  5. South Branch Little River
  6. Ellsworth Creek
  7. Trapper Creek
  8. Cummings Creek
  9. Oak Creek
  10. Middle Fork Teanaway River
  11. Umtanum Creek
  12. North Fork Sullivan Creek

Basin Site Monitoring

At least ten basin or watershed sites were monitored annually, based on the needs of Ecology's Regional Offices. Basin sites were monitored by region according to the following schedule:

Central Regionsummer 2002
Eastern Regionsummer 2003
Southwest Regionsummer 2004
Northwest Regionsummer 2005

Special Studies

We receive several requests each year from within the Department of Ecology to provide detailed investigations of biological condition in portions of a watershed.  These requests are based on a need for biological information that will assist in regulatory decisions and can be used in enforcement of environmental law or to revise existing regulations.  Some of the work we do helps make decisions on habitat enhancement efforts like in the Yakima Floodplain Gravel Pit Mining partnership; a study initiated with several state, local, and federal partners to determine if reconnection of old gravel pits would provide greater habitat availability to salmonids and their food source.  Another study has been focused on evaluating the positive impacts habitat restoration has on stream communities following a debris torrent that removed existing usable habitat in a coastal stream.  We continue to evaluate sampling strategies: their comparability to each other, and the sensitivity in detecting specific impacts to stream communities.  The special studies supplement basic information gathered through the "routine" monitoring portion of this project and are focused on finding the source and nature of impairments to stream ecosystems.

Examples of completed special studies include Mid-Sol Duc and Quilceda/Allen.

Click to go to online reports

Access to Data

Field Methods

Photos showing field methods are available.


For more information on Ecology's ambient stream biological monitoring project, contact Chad Larson, (360) 407-7456.