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Biological Monitoring

Ancylidae Brachycentridae Corbiculidae


The Virginia Department of Environmental Quality's (DEQ) Freshwater Biological Monitoring Program uses the benthic macroinvertebrate community to assess the ecological health of freshwater streams and rivers. Benthic macroinvertebrates are invertebrate organisms such as insects, crustaceans, snails or worms that live on the bottom of streams and rivers which are large enough to be seen with the naked eye. Because many of the organisms that make up these biological communities are extremely sensitive to pollutants, they often respond to changes in water quality caused by the introduction of various contaminants into a water body from point or non-point source pollution. In essence, benthic macroinvertebrates are considered to be virtual "living recorders" of water quality conditions over time. Analysis of the community of these organisms provides a measure of the overall water quality of a particular water body segment. The assessment is made by comparing the community of benthic macroinvertebrates collected at a "reference" stream where there are no significant disturbances, to the community of benthic macroinvertebrates collected at the stream under consideration.

DEQ's Freshwater Biological Monitoring Program is conducted out of six regional offices located throughout Virginia. These offices are located in Abingdon, Roanoke, Harrisonburg, Woodbridge, Glen Allen and Virginia Beach, each of which is staffed with two Regional Biologists, except Virginia Beach which has only one regional biologist. For contact information, visit DEQ's regional biologist contacts page.

DEQ began biological monitoring in the 1970's and the program has continued to change and evolve over time. Historically, the biological monitoring program consisted of two types of stations: repeated sampling at fixed (permanent) stations each year during the spring and fall seasons and targeted stations. These fixed stations were comprised of a reference network of ecoregional, watershed or upstream stations, selected to be representative of natural, least impaired conditions characteristic of specific stream types, against which benthic communities from targeted streams were compared to determine overall water quality. Targeted stations typically were selected to investigate specific areas or problems; for example, stream reaches below point source discharges that were generally a component of special studies designed to measure the effects of the point source. Where significant problems were found, these stream segments are placed on the 303(d) List of Impaired Water Bodies.

Biological assessments were based on Rapid Bioassessment Protocol (RBP) II procedures. These follow specific guidelines in the USEPA document "Rapid Bioassessment Protocols for Use in Streams and Rivers" (Plafkin et al. 1989).

Recent Developments in the Biological Monitoring Program

Non-Coastal Streams

In 2003, an index of biotic integrity (IBI) was developed for Virginia freshwater non-coastal streams using historical data collected at reference and stressed streams in 1994-1998, and was tested against additional data collected in 1999-2002, with the help of EPA Region III and Tetra Tech, Inc., Fairfax, Virginia. This review has resulted in the development of a stream condition index for use in assessing wadeable non-coastal streams. It is based upon recent advances in bioassessment methods contained in "Rapid Bioassessment Protocols for Use in Wadeable Streams and Rivers, Second Edition" (USEPA, 1999). This index, known as the Virginia Stream Condition Index (VSCI), a multi-metric calculation of benthic integrity into a single value, or numerical score, resulted in a single reference condition for the entire non-coastal portion of the state against which all future benthic samples will be compared. The development of this index is considered a significant step in the advancement of the biomonitoring program to address a wide range of monitoring and assessment needs. Tetra Tech produced a final written report titled "A Stream Condition Index for Virginia Non-Coastal Streams" (PDF) in September 2003. The report describes the procedures undertaken in the development of this new index. An electronic version is available by clicking the link above. Photocopies are available through the DEQ contact listed below; however, there is a charge for photocopy versions.

Using an independent, new probabilistic database (sample n=350) with data collected from 2001-2004, Virginia has validated the Virginia Stream Condition Index (VSCI) using a spatially diverse (ecoregionally and stream size) data set free of psuedoreplication. This probabilistic data has allowed the Virginia Department of Environmental Quality (DEQ) to narrow data gaps and test the VSCI against many classification variables, which include season, stream size, ecoregion, bioregion, river basin, and sampling technique. DEQ also reviewed the recommended best standard values for the eight core metrics. This report is Using Probabilistic Monitoring Data to Validate the Non-Coastal Virginia Stream Condition Index which focuses on the validation of the VSCI and proposes assessment recommendations.

Mid-Atlantic Coastal Plain Streams

In 1995, Virginia DEQ participated in a multi-state effort that was used to revise the methods and metrics used in assessing freshwater streams in the mid-Atlantic coastal region (Maxted et al. 2000). A report "Assessment Framework for Mid-Atlantic Coastal Plain Streams Using Benthic Macroinvertebrates" (MACS report) and the "Field and Laboratory Methods for Macroinvertebrates and Habitat Assessment of Low Gradient, Nontidal Streams" are available. These procedures and metrics are being used to assess the streams in the coastal plain portion of Virginia and is based upon the same assessment principles found in the 1999 EPA guidance document.

Self Assessment

A self assessment of the Biological Monitoring program was conducted by DEQ Biologists in 2008 to gain a better understanding of what the program needs to move forward in the future. This document (Benthic Biomonitoring Self-Assessment) was created to provide focus and direction to biological monitoring in Virginia for the next several years. DEQ Central Office and Regional Office staff met from February 2008 through March 2009, to identify needed guidance and data management tools related to the Biological Monitoring Program.

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Virginia Department of
Environmental Quality
P.O. Box 1105
Richmond, VA 23218
(804) 698-4000

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