At least one sediment sample is collected at each station where fish tissue are sampled and analyzed for a suit of bioaccumulative chemical contaminants. These include selected heavy metals, selected non-halogenated organic compounds (PAHs) and halogenated organic compounds (DDT, Chlordane, PCBs, etc.)

The analytical data are assessed to determine the human health risks for individuals who may consume fish from state waters and to identify impaired aquatic ecosystems. The Virginia Department of Health uses the data generated by the program to determine the need for issuing fish consumption advisories. The Department of Environmental Quality and other state and federal agencies also use the data to assess the environmental quality of Virginia's waters.

Fish Tissue and Sediment Monitoring Program Background 

Objectives

The primary objectives of the Fish Tissue and Sediment Contaminants Monitoring Program are to collect the data required to assess the human health risks for individuals who may consume fish from state waters and to identify impaired aquatic ecosystems. The Virginia Department of Health uses the data generated by the program to determine the need for fish consumption advisories. The Department of Environmental Quality and other state and federal agencies also use the data to assess the environmental quality of Virginia's water. For example, fish tissue and sediment data have been used to support the Commonwealth's water quality goals and provide documentation and compliance with the Clean Water Act.

Methods

The objective is met through a cost efficient two-tiered sampling strategy consistent with federal guidance for fish tissue and sediment contamination monitoring programs. Tier I is a screening study of a relatively large number of sample stations to identify sites where concentrations of chemical contaminants in stream sediments and/or the edible portions of commonly consumed fish indicate potential aquatic ecosystem impairment and/or significant health risks to human consumers. If Tier I results indicate problems exist, then a second more intensive Tier II study is initiated to determine the magnitude and geographical extent and potential source(s) of contamination in the sediments and/or fish. Established Quality Assurance and Quality Control protocols are used throughout the program.

Tier I

Tier I sampling stations are selected on a rotational river basin approach among the fourteen river basins in Virginia. Approximately, 50 to 100 stations are selected among two or three river basins per year depending on available funding. Several criteria are used to select the sample stations, and they include: correspondence with the Department of Environmental Quality-Waste division to identify contaminated waste sites that may impact tissue and sediments in aquatic environments, regional office recommendations, extensive literature searches, important recreational and/or commercial fisheries, proximity to point source discharges, and spatial distribution between sample stations.

An attempt is made to collect three to five tissue composite samples (5-10 individuals of the same species per composite) at each station. The individuals in each composite should be approximately the same size, i.e., the shortest specimen should be within 75% of the longest specimen. A top level predator (e.g. largemouth bass) a mid-level predator (e.g. bluegill sunfish) and a bottom feeder (e.g. catfish species) are usually targeted at Tier I sample stations. Adult fish are collected because their potential for exposure to environmental contamination has occurred over a longer period of time compared to juvenile fish. Fish are typically collected by boat or backpack electrofishing equipment, however, other methods may be employed (e.g. trot lines, gill nets, etc.). Fish collected are weighed (g), measured (cm - total length), wrapped in aluminum foil, and placed in plastic bags. During sample processing, the contract laboratory removes filets (skin on) of fish of the same species and combines the filets to make a composite sample. Tissue samples for each species are analyzed for organic compounds, trace metals, percent moisture, and percent lipid.

Tier I analytical results for chemical contaminants in fish tissue are expressed in wet-weight basis and are compared Screening Values that are computed using risk assessment techniques for non-carcinogen and carcinogen effects. Typical Screening Value calculations use the following assumptions: a 10-5 risk level adopted by the State Water Control Board; a human body weight of 70 kg (average adult body weight), a lifetime fish consumption rate of 6.5 g/d (general U.S. population), and a reference dose for non-carcinogenic and an oral dose slope for carcinogenic effects (EPA Integrated Risk Information System - IRIS database system).

Sediment samples are also collected at the sample station in pre-cleaned sample containers using established protocols. The fish and sediment samples are frozen until processed by the contract laboratory. The sediment samples are analyzed for organic compounds, trace metals, total organic carbon.

Analytical results for chemical contaminants in sediment are expressed in dry-weight basis and are compared to Effects Range-Median Screening Values provided by the National Oceanic and Atmospheric Administration to assess the potential effects of sediment contamination to aquatic life.

Tier II

If Tier I analytical results indicate Screening Values have been exceeded and Quality Assurance and Quality Control measures have been achieved, then an intensive Tier II investigation may be conducted. The unique features of Tier II investigations are sample replication and multiple station sampling which allows statistical confidence to be placed around the data points and contaminants spatial distribution characterization, respectively. Hence, Tier II investigations typically involve laboratory analysis of five to ten individual filet samples or multiple composite samples of two or three top or mid-level feeders and one or two bottom level feeders at each station to increase statistical power. As in Tier I data analyses, Tier II analytical results are compared to the risk based Screening Values, and appropriate Quality Assurance and Quality Control procedures are followed.

Fish Tissue and Sediment Data Application

Fish tissue and sediment data collected for the monitoring program are analyzed and reports are generated by the Department of Environmental Quality-Office of Water Quality Standards. Fish tissue data are compared to the Department of Environmental Quality Screening Values which are processed using a risk based approach conforming to EPA guidelines. Sediment data are compared to National Oceanic and Atmospheric Administration sediment Effects Range-Median Screening Values. Sites that exceed Effects Range-Median Screening Values indicate relatively moderate to high degrees of sediment contamination. Study reports are distributed to the Virginia Department of Health which issues fish consumption bans or advisories if deemed necessary. In addition, reports used primarily by water quality managers to help identify areas of water quality impairment are sent to the appropriate central and regional Department of Environmental Quality offices. A summary of fish tissue and sediment collections and analyses is also included in the biennial Water Quality Assessment 305 (b) Report to EPA and Congress as required by the Federal Clean Water Act. The 305 (b) report serves as the Commonwealth's primary problem assessment, and directs continuous planning and implementation activities, in coordination with the 305 (b) Action Plan, Water Quality Management Plan, and the Priority Water Bodies 303 (d) Report. On July 1, 1997, Virginia Senate Bill No. 1122 was passed into state law. The law expands fish tissue and sediment monitoring, data application in water quality assessment, and reporting requirements by the Department of Environmental Quality. The law provides for "...increased use, as necessary, beyond 1996 levels, of sediment monitoring...and fish tissue monitoring, and provides for specific assessments of water quality based on the results of such monitoring" in 305 (b) and 303 (d) reports. Currently, the 305 (b) reporting requirements for of the new law are being met. To meet the 303 (d) reporting requirements of the new law, Office of Water Quality Program proposes guidelines in the 2002 Water Quality Assessment Guidance Manual.

Project Organization and Responsibility

More Information

• 305(b)/303(d) assessment reporting requirements (pdf)
• Federal guidance for fish tissue 
• Fish tissue and sediment toxics evaluation (pdf)
• Integrated Risk Information System
• Risk assessment and fish consumption limits