EPA: A Primer on Using Biological Assessments to Support Water Quality Management


Here’s the link to the publication from the Environmental Protection Agency. Here’s an excerpt:

This guide serves as a primer on the role of biological assessments in a variety of water quality management program applications, including reporting on the condition of the aquatic biota, establishing biological criteria, and assessing the effectiveness of Total Maximum Daily Load determinations and pollutant source controls. This guide provides a brief discussion of technical tools and approaches for developing strong biological assessment programs and presents examples of successful application of those tools.

The objective of the Clean Water Act (CWA), and water quality management programs generally, is “to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” Although we have achieved major water quality improvements over the past four decades and have reduced the discharge of many toxic chemicals into our nation’s waters, many environmental challenges remain, such as loss and fragmentation of habitat, altered hydrology, invasive species, climate change, discharge of new chemicals, stormwater, and nitrogen or phosphorus (nutrient) pollution. In the face of such challenges, how can we best deploy our water quality programs to meet the vision of the CWA for protection of aquatic life?
Measuring the condition of the resident biota in surface waters using biological assessments and incorporating that information into management decisions can be an important tool to help federal, state, and tribal water quality management programs meet many of the challenges.

Biological assessments are an evaluation of the condition of a waterbody using surveys of the structure and function of a community of resident biota (e.g., fish, benthic macroinvertebrates, periphyton, amphibians) (for more information, see Biological Assessment Key Concepts and Terms)1. Assessments of habitat condition, both instream and riparian, are typically conducted simultaneously. Such information can reflect the overall ecological integrity of a waterbody and provides a direct measure of both present and past effects of stressors on the biological integrity of an aquatic ecosystem. The benefit of a biological assessment program is based in its capability to:

– Characterize the biological condition of a waterbody relative to water quality standards (WQS).

– Integrate the cumulative effects of different stressors from multiple sources, thus providing a holistic measure of their aggregate effect.

– Detect aquatic life impairment from unmeasured stressors and unknown sources of impairment.

– Provide field data on biotic response variables to support development of empirical stressor response models.

– Inform water quality and natural resource managers, stakeholders, and the public on the environmental outcomes of actions taken.

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