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Uses of Data

Biocriteria Links

Set Protection and Restoration Goals

Biological information is used to set biologically-based water quality goals.   Water quality standards, in essence, reflect the public's intentions for the condition and level of functioning they desire for each body of water. Biocriteria make it possible to set scientifically based, biological goals which provide a guidepost for comparing actual against desired conditions and help determine if a chosen level of ecosystem health is being sustained. Bioassessment data help in setting goals by defining what kinds of aquatic communities exist under a variety of conditions; that is, it tells us the specific organisms that could be or should be present in different bodies of water. For example, a river may not currently support a healthy salmon population, but it once did and under restored conditions could do so again. Restoring the salmon and, other biological organisms, means restoring the river.

The Clean Water Act (CWA sections: 101(a); 303(c)(2)(b); and 304(a)1,2, and 8) calls for states to set water quality goals for all their waterbodies. These goals are embodied in state standards that:

The designation of aquatic life uses is the key intersect between the CWA's long term goal to achieve biological integrity and a state or tribal water quality standards program.

Biological integrity is commonly defined as "the ability to support and maintain a balanced, integrated, and adaptive community of organisms having a species composition, diversity and functional organization comparable to those of natural habitats within a region" (Karr, J. R. and D. R. Dudley. 1981. Ecological perspectives on water quality goals. Environmental Management 5: 55-68).

The tiered aquatic life uses, supported by numeric criteria, can be thought of as defining different management levels of biological condition across a quality continuum that ranges between "natural" or "minimal human impact" to the minimum federal standard.

Designated uses to support aquatic life can cover a broad range, or continuum, of biological conditions with some waters being closer to the ideal of "natural" or "minimal human impact" than others.

WHAT IS THE VALUE OF TIERED AQUATIC LIFE USE DESIGNATIONS AND WHAT IS THE ROLE OF BIOASSESSMENT IN DEVELOPING THEM?

Tiered aquatic life use designations allow for appropriately varying levels of protection of a jurisdiction's surface waters. This concept reflects the reality of the "gray" area that exists between "totally pristine" and "completely degraded" water quality conditions. The use of bioassessment tools provides a means of directly assessing biotic integrity to establish the tiered use designations and then a method that can be consistently applied in a standardized manner to measure whether these uses are being attained. Biocriteria, used in the framework of tiered aquatic life use designations, help shift the regulatory focus from performance-based standards to impact-based standards. The benefits of this shift include:

  • Less reliance on regulators to make "judgment calls"
  • More flexibility for discharges to exercise options in meeting goals
  • More equitable regulation of point and non-point sources
  • Better opportunity for public understanding of, and input to, resource use decisions

Tiered Aquatic Life Use Designations

Historically, water quality policy has relied upon performance-based standards to establish allowable pollutant loads, monitoring requirements, and enforcement actions. Performance-based standards focus on individual pollutants and are used to regulate specific activities. These types of standards had - and continue to have - an essential role in maintaining and improving water quality. But they don’t go far enough because they don’t address the broad goal of ecological integrity. The use of impact standards or outcome indicators - requiring that a certain result be achieved - overcomes many of the deficiencies of performance standards and serves a complementary function that provides flexibility, realism, and a direct measure of ecological integrity.

However, it is of critical importance that impact standards be specific well-defined and allow for waters of different natural quality and different desired uses. Simply stating that there should be "no impairment of aquatic life" or "no change from reference conditions" and applying this standard to all waters within a jurisdiction is unrealistic, prevents informed participation from stakeholders, and can allow conditions to exist from unacceptably degraded to unnecessarily overprotected. Both Maine and Ohio have recognized this problem and have developed a tiered system of aquatic life use designations, which make use of the power of biological information to develop graduated levels of protection.

Case studies demonstrate how the biological information implicit in tiered aquatic life use designations can improve the effectiveness and efficiency of water quality programs.

Biological Indicators

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