Expert Interview With Dr. Jerry Diamond, Ecotoxicology and Risk Management Expert

Dr. Jerry Diamond, Tetra Tech’s Director of Ecotoxicology, has more than 30 years of experience in human health and ecological risk assessments, aquatic ecology, environmental toxicology, water quality criteria and standards, and design and interpretation of environmental assessments. He has developed and managed more than 300 environmental assessments involving various types of pollutant sources, including treated wastewater effluents, industrial and municipal stormwater, combined sewer overflows (CSOs), sanitary sewer overflows (SSOs), and nonpoint source runoff from urban and agricultural sources. Dr. Diamond has directed many successful toxicity identification evaluations for industrial and municipal wastewater facilities. He also has developed site-specific water quality criteria and standards and wastewater discharge permit limits for dissolved oxygen, several metals, ammonia, selenium, and other constituents for more than 100 sites around the United States.

In addition to assisting U.S. Environmental Protection Agency (EPA), U.S. state and local agencies, and commercial clients with various water quality issues, he has worked as an expert on water quality and toxicity issues in other countries including Canada, Brazil, Japan, Korea, and Thailand.

How do ecotoxicology and risk assessment work together?

Risk assessment is the process we use to determine whether a certain site, chemical, or environmental sample—such as a treated wastewater effluent—is likely to have detrimental effects on biota (plants and animals) or human health. In ecological risk assessments, we use information based on ecotoxicology to help us tell whether a site or chemical may impact biota.

Ecotoxicologists study how organisms can be exposed to various chemicals; what happens when they are exposed and how the chemical interacts with the organism; and the effects that may be expected to different types of organisms as well as ecosystems as a whole. Chemicals can have different effects on biota depending on the physical properties of the chemical, the source of the chemical, and the ecosystem that is being evaluated. Understanding how different chemicals behave in the environment and which types of species are most sensitive helps conduct more efficient, smarter risk assessments.

Tetra Tech’s nationally accredited ecotoxicology laboratory associated with our office in Owings Mills, Maryland, provides much of the information needed to help address uncertainties in ecological risk assessments as well as helping other types of projects such as environmental impact studies, dredge disposal management studies, and remedial investigations at Superfund sites.

What are some solutions you provided that a client successfully implemented?

My team of scientists and I have assisted several municipal and industrial wastewater treatment authorities in solving effluent toxicity issues using a combination of ecotoxicology expertise and knowledge of different types of wastewater operations. In one case, through targeted in-plant sampling as well as toxicity analyses of different waste streams, we determined that a biocide used in non-contact cooling water was responsible for observed effluent toxicity. By replacing the biocide with a less toxic (and less expensive) alternative, the plant was compliant with state and federal regulations and saved money as well.

In another example, we used ecotoxicology, aquatic ecology, and risk assessment principles to determine that observed declines in threatened and endangered mussel populations in the Clinch River watershed in Virginia were not due to pesticides or some other chemicals as thought. The declines were due to increased sedimentation and occasional toxic spills from a number of sources that could be controlled through best management practices. The agencies used the results of the risk assessment to identify high priority areas in most need of protection and have instituted some beneficial changes in the watershed including better communication of the risks to people living and working in the watershed.

How are ecotoxicology and risk assessment services used to address our clients’ needs?

Both ecotoxicology and risk assessment are very important front-end services for Tetra Tech’s clients and have been since the company’s inception. At Tetra Tech, we routinely use ecotoxicology to help inform the risk assessments we do in terrestrial settings, streams and rivers, lakes, estuaries, and even the arctic tundra. We have used risk assessments to help our clients better manage their resources and identify cost-effective options for reducing expected impacts. Our experts have used ecotoxicology and risk assessments in the mining and oil and gas sectors, environmental assessment projects involving either proposed projects or legacy activities in the industrial sector, and Department of Defense sites. We have assisted EPA in expanding the risk assessment concept to watershed or regional scales and not just specific sites, which has the added value of being able to include some non-traditional risk factors such as invasive species, poor habitat quality, hydrological changes, and climate change.