Index of Biological Integrity as a Water Quality Measure An Overview

Water Quality/Impaired Waters 3.23 • November 2008

iological monitoring tracks the health of plants, fish, insects, and small organisms in lakes, streams Citizen involvement, B and rivers. Researchers use several education and measures of a biological community to outreach, and pollution prevention create an Index of Biological Integrity are key components (IBI). A typical IBI developed for fish will of all TMDL measure eight to 12 attributes related to the implementation diversity and types of species present, plans. including feeding, reproduction, tolerance to human disturbance, abundance, and condition. These help distinguish between natural processes and changes caused by Biological life is human activities. For example, species subjected to the considered tolerant of some form of cumulative effects of all activities, and pollution, such as sedimentation, could including: chemicals in wastewater represents the form a “tolerant” measure. Polluted or treatment discharges; agricultural runoff of condition of their impaired waters would tend to have more pesticides, nutrients, and sediment; flow aquatic environment. of these tolerant species. changes from stream channelization, dams, and artificial drainage; and habitat changes Ratings assigned to each measure are from agricultural, urban, and residential summed up in a score indicating the development. Testing water quality by MPCA Offices: underlying biological integrity or “health” chemistry only can fail to detect these Rochester: of a particular water body. A high IBI wider impacts. 507/285-7343 score indicates biological species similar to Mankato: least-impacted (reference) sites of Aquatic organisms spend all or a vast 507/389-5977 Marshall: comparable size and type in the same majority of their life cycles in the water. 507/537-7146 geographic region. A low IBI score The variety of species is a reflection of the Willmar: indicates the species are significantly cumulative effects of all natural and 320/214-3786 different or degraded compared with human-caused influences on that Detroit Lakes: 218/847-1519 regional reference sites. Narrative waterbody, whether or not the impact is Brainerd: descriptions can be used to rate the chemical, physical, or biological. 218/828-2492 integrity of a site as excellent, good, fair, Therefore, biological monitoring is often Duluth: poor, or very poor. able to detect water quality impairments 218/723-4660 that other methods may miss or Metro: 651/296-6300 Why Perform Biological underestimate. Toll-Free Number: Monitoring? 800/657-3864 To ensure the integrity of surface waters, Fish we must understand the relationship Fish are widely-used and useful for between human activities and their effects measuring water resource quality. They are on specific aquatic life. Pollution in surface waters comes from many sources wq-iw3-23

Minnesota Pollution Control Agency • 520 Lafayette Rd. N., St. Paul, MN 55155-4194 • www.pca.state.mn.us 651-296-6300 • 800-657-3864 • TTY 651-282-5332 or 800-657-3864 • Available in alternative formats typically present even in the smallest streams and are are taken into account. However, determining the easily sampled and identified with the proper equipment primary stressors that are leading to the impairment and training. The Clean Water Act mandates “fishable” requires an additional step. This step, often referred to as waters and the public widely recognizes fish for their stressor identification, can provide the linkage between economic and aesthetic value. Fish are diverse and have the impaired community and the numerical, load-based, a wide range of habitat needs. Some are sensitive to water quality information needed for completing a Total changes in water temperature, bottom composition, Maximum Daily Load (TMDL). stream flow, or water chemistry, while others are tolerant of changes in their environment. The fish food More Information chain ranges from plankton to other fish. The variety of All currently-available IBI documents: fish species makes them excellent indicators of water www.pca.state.mn.us/water/biomonitoring/index.html quality. Aquatic life use support assessment methodology Invertebrates described in the MPCA’s Guidance Manual for Aquatic invertebrates, also called benthic Assessing the Quality of Minnesota Surface Waters: macroinvertebrates or benthos, include insect larvae, hwww.pca.state.mn.us/publications/wq-iw1-04.pdf crayfish and other crustaceans, snails, clams, aquatic worms and leeches. They are found in all types of Basis for using the health of the biological community surface waters, including large rivers, small streams, for assessment is the narrative water quality standards in lakes and wetlands. They are most commonly found Minnesota Rules Chapter 7050: living on submerged aquatic vegetation, woody debris, https://www.revisor.leg.state.mn.us/rules/?id=7050 or rocks and cobbles, but are also found in the water column. A very diverse group, benthic Biota TMDL Protocols and Submittal Requirements: macroinvertebrates, display a wide range of sizes, habitat www.pca.state.mn.us/publications/wq-iw1-23.pdf requirements, life histories, and sensitivities to water quality impairment. Some are sensitive to changes in Biological Monitoring Streams: Fish Monitoring: bottom composition; others are sensitive to changes in www.pca.state.mn.us/water/biomonitoring/bio-streams- dissolved oxygen. Some require cold water fish.html temperatures, while others can tolerate a wide range. This makes benthic macroinvertebrates excellent MPCA Total Maximum Daily Load Program: indicators of human impact on aquatic systems. www.pca.state.mn.us/water/tmdl/index.html Researchers use hand held dip nets and artificial habitats to collect invertebrate samples.

Impairment Listing Section 303(d) of the federal Clean Water Act requires states to identify and list impaired waters. A final determination of biological impairment is based on all available information, prior to being listed. This includes habitat quality, available water chemistry data, and biological condition of nearby upstream and downstream segments, local land use information, and other watershed data. The MPCA presents this information to a group of water quality experts who consider all of the available data when making the listing decisions.

Biological impairments differ from some traditional water quality impairments in that the impaired biotic communities are indicators of responses to pollution rather than causes. The advantage of using a response indicator in making an overall evaluation of ecosystem health is that the cumulative effects of multiple stressors

Index of Biological Integrity-Overview • Water Quality/Impaired Waters 3.23 • November 2008 page 2