Healthy waterbodies exhibit ecological integrity, representing a

natural or undisturbed state. As the

diagram to the right illustrates,

ecological integrity is a combination of three components:

chemical integrity, physical

integrity, and biological integrity.

When one or more of these

components is degraded, the

health of the waterbody will be

affected and, in most cases, the

aquatic life living there will

reflect the degradation.






The identification of water

quality degradation requires

appropriate monitoring tools.

Such tools help us detect and characterize the cause and source of chemical, physical

and biological impairment. Bioassessments are the primary tool to evaluate the biological condition of a waterbody. Bioassessments consist of

surveys and other direct measurements of aquatic life—

aquatic vegetation and algae, fish, insects, crayfish,

salamanders, frogs, worms, snails, mussels, etc.—in the

waterbody. Bioassessments, along with other physical and

chemical assessments, are crucial for evaluating the

health of a waterbody.

Aquatic life integrates the cumulative effects of

different stressors such as excess nutrients, toxic

chemicals, increased temperature, and excessive

sediment loading. Therefore, bioassessments allow us

to measure the aggregate impact of the stressors.

Because biological communities respond to stresses

over time, they provide information that more rapidlychanging water chemistry measurements or toxicity

tests do not always produce. As such, bioassessment

United States Office of Water EPA 822-F-02-006

Environmental Protection (4304) Summer 2002

Agency

	
















	





	



	

	








	

	

















		



	











	
	



	


	


	



			

	



 


	

	
	
		

				





	
	
	




	
	

	
	

	

		







	

	

	

		

	
	





	


		
	


		
		
	

			




	

provides a more reliable assessment of long-term

biological changes in the condition of a

waterbody. The central purpose of assessing

biological condition of aquatic communities

is to determine how well a water body

supports aquatic life.

Bioassessments reflect the condition of overall

ecological integrity (i.e., when the biology is healthy,

typically the chemical and physical components of a waterbody are also

in good condition). Therefore, bioassessments directly assess the condition of

ecosystem health, a primary goal of the Clean Water Act (CWA).

Biologists and other natural resource scientists use accepted scientific principles to derive biocriteria from bioassessment data. Biocriteria are narrative descriptions or numerical values that states and tribes can adopt into water quality standards to describe a desired condition for the aquatic life in waters they have

designated for aquatic life use. The standards, in turn, are used along with

chemical and physical criteria to better manage water resources.




The use of biological assessment and criteria for managing the Nation’s

waterbodies is progressing and is equipping the states, tribal nations, and EPA

with a more effective set of monitoring tools for protecting the ecological integrity of our water resources. In recent years, progress has been made in using

bioassessments to establish biocriteria. In 1994, twenty states were beginning a

biological assessment program for streams and rivers, and fourteen states had

biological programs in place. However, only eleven were developing or had

developed biocriteria based on their monitoring

programs. By 2001, most states and several tribes

had established biological monitoring programs

for streams and small or wadeable rivers and were

using quantitative biocriteria. The development

of biocriteria for bodies of water other than

streams and wadeable rivers is more recent.

	






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	Maximum

MinimumBiological Health

Fair-Poor

Good -Fair

Good

Very Good

Gradient of Disturbance

Exceptional

Narrative Description of Biological Condition

Tiered Aquatic Life Uses

Limited

Resource

Waters

High

Disturbance

Low

Disturbance

Modified

Warmwater

Habitat

Warmwater

Habitat

Exceptional

Warmwater

Habitat

Very Poor

Poor











 







	

Bioassessments provide crucial

water quality information for

managing complex water

quality problems. Many

natural, chemical, and

physical integrity factors

directly influence biological integrity. Hence,

attaining biological

integrity reflects good

waterbody health. When

human activities disrupt

chemical and physical

integrity, biological

integrity is also compromised, and ecological

health declines.

Bioassessments are the

tool for measuring

biological condition and

serve three primary

functions:

1. screening or initial

assessment of

conditions

2. characterization of

impairment and

diagnosis; and

3. trend monitoring to

evaluate improvements or further

degradation.

One use of bioassessments is to help states

and tribes develop

expectations for acceptable biological conditions. This is done

through a technical

process of establishing

aquatic life goals, referred to as aquatic life

uses (ALU). Biological assessments allow various

levels of ALUs, so that one set of standards supports

intact communities in a waterbody, and other sets of

standards establish restoration goals for rural or urban

streams or other altered ecosystems. Using several

 



	



types, or tiers, of ALUs allows states and tribes to

allocate limited resources to waterbodies in proportion

to their need for protection. The figure above illustrates

one such approach.









Biocriteria programs begin with a strong

bioassessment and biomonitoring program.

Expertise in ecological principles is required to

develop and implement biocriteria. State agencies vary in the level of resources they invest in

the process. As an example, the developmental

costs for stream bioassessment for Maine (benthic

macroinvertebrates), Vermont, and Ohio (fish

and benthic macroinvertebrates) were similar.

Development and implementation of a

bioassessment framework into water quality

programs took 7 to 11 years for these states. This

timeframe will depend on resource investment

and the ability to gather and analyze data. Most

states are able to develop the technical framework for bioassessment in less than five years.

Once the bioassessment framework is in place,

the maintenance or continued monitoring is

generally reduced.

Programs of three states are highlighted as

examples of development and maintenance costs

for bioassessment. For Vermont and Maine, the

equivalent of 4 and 3 FTEs, respectively, are

dedicated to bioassessment and biocriteriarelated activities. For Ohio, a larger state with

a higher number of industrial and municipal

discharges to their waters, 12 FTEs are allocated to the bioassessment and biocriteria program for the state’s streams and

rivers. Although Ohio expends more effort than Vermont and Maine, the ecological assessment component of the state’s entire water resources program is

only 7% of their personnel. Ohio’s ecological assessment program includes all

bioassessment and biocriteria activities for all waterbodies–not just streams.

	




The concept of ecological integrity is embedded in the statutory and regulatory

structure of clean water law in the USA. One of the Clean Water Act’s fundamental long-term goals is to protect aquatic resources by maintaining and

restoring ecological integrity (combination of physical, chemical, and biological

integrity). Bioassessments are the tool for states and tribes to determine the

health of their waterbodies and achieve the level needed to support the

waterbody’s designated uses.

Under the CWA, states and tribes must designate aquatic life uses for their

waters (i.e., environmental goals) that will achieve the purposes and objectives

of the Act. This includes protecting and enhancing biological integrity and

adopting the criteria necessary to protect those uses. Designated uses supporting

aquatic life cover a broad range, or continuum, of biological conditions, with

some waters being closer to an ideal of natural, undisturbed (biological integrity) status or condition.

0

2

4

6

8

10

12

14

16

Maine

(benthic only)

Ohio

(benthic & fish)

Program

Development

Program

Maintenance

Vermont

(benthic & fish)

Cost of Program in FTEs

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%

Permitting/

Compliance

Assistance

59%

Watersheds/

NPS/WQS

14%

Administration/

Management

1%

Water Quality

Modeling/TMDL

6%

Ambient

WQ/Compliance/

Complaint

7%

Biological

Assessment

Program 7%

Administration

6%

Monitoring and

Assessment

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Barbour, MT, J Gerritsen, BD

Snyder, and JB Stribling. 1999.

Rapid Bioassessment Protocols for

Use in Streams and Wadeable

Rivers: Periphyton, Benthis

Macroinvertebrates and Fish. U.S.

Environmental Agency, Office of

Water, Washington, DC. EPA

841-B-99-002.

Biological Criteria: Guide to

Technical Literature. U.S.

Environmental Protection Agency,

Office of Water. July 1991. EPA/5-

91-004.

Biological Criteria: National

Program for Surface Waters. U.S.

Environmental Protection Agency,

Office of Water, Washington, DC.

1990. EPA-440/5-90-004.

Biological Criteria: Research and

Regulation—Proceedings of a

Symposium. U.S. Environmental

Protection Agency, Office of

Water. July 1991. EPA-440/5-91-

003.

Biological Criteria: Technical

Guidance for Streams and Small

Rivers. U.S. Environmental

Progection Agency. May 1996.

EPA 822-B-96-001.

Danielson, TJ. 1998. Wetland

Bioassessment Fact Sheets. U.S.

Environmental Protection

Agency, Office of Water,

Washington, DC. EPA 843-F-98-

001.

Estuarine and Coastal Marine

Waters: Bioassessment and

Biocriteria Technical Guidance.

December 2000. U.S.

Environmental Protection

Agency, Office of Water,

Washignton, DC. EPA 822-B-00-

024.

Lakes and Reservoir

Bioassessment and Biocriteria

Technical Guidance Document.

U.S. Environmental Protection

Agency, Office of Water. August

1998. EPA 841-B-98-007.

Macroinvertebrate Field and

Laborator Methods for Evaluating

the Biological Integrity of Surface

Waters. U.S. Environmental

Agency, Office of Water. 1990.

EPA/600/4-90/030.

Regionalization as a Tool for

Managing Environmental

Resources. U.S. Environmental

Protection Agency,

Environmental Research

Laboratory, Corvallis, OR. July

1989. EPA/600/3-89/060.

Standard Operating Procedures

for the Collection of and

Laboratory Identification of

Freshwater Benthis

Macroinvertebrates. U.S.

Environmental Protection

Agency, Region 5, Chicago, IL.

1989.

Standard Operating Procedures

for Conducting Rapid Assessment

of Ambient Water Quality

Conditions Using Fish. U.S.

Environmental Protection

Agency, Region 5, Chicago, IL.

Stressor Identification Guidance

Document. U.S. Environmental

Protection Agency, Offices of

Water and Research and

Development. December 2000.

EPA 822-B-00-025.

Summary of State Biological

Assessment Programs for Rivers

and Small Streams. U.S.

Environmental Protection

Agency, Washington, DC. 1996.

EPA 230-R-96-007.

The Volunteer Monitor’s Guide

to Quality Assurance Project

Plans. 1996. U.S. Environmental

Protection Agency, Office of

Water, Washington, DC. EPA

841-B-96-003.

	




	






	




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