About the Company
Hennessy Consulting LLC is owned by Dan Hennessy, an environmental scientist and fisheries biologist with more than 25 years of professional experience as a project manager, lead scientist, aquatic toxicology laboratory director, statistician, and field team leader. He has led and supported a wide range of project teams conducting contaminated site investigations, risk assessments, biological monitoring, and habitat restorations. As a consultant, his clients have included individual property owners, small businesses, local, state, and federal government agencies, and energy, mining, and maritime industries.
Dan is a member of the Society of Environmental Toxicology and Chemistry where at national and regional meetings he has had the pleasure of presenting several times and learning about new and continuing research, improved methods, and cutting-edge technologies. He counts himself as lucky to work with interesting people at something he likes and to have the privilege of advancing the environmental restoration economy in the Pacific Northwest and elsewhere in the United States.
Dan recharges by being in nature and he seeks new places to visit, especially those close to water. Dan enjoys photographing and filming natural and urban landscapes, listening to and playing music, gardening, and spending time with his family.
On the Services page, you can read more about the site cleanup environmental services provided by Hennessy Consulting LLC, and the process to add us to your team.
Work Experience
April 2025 – present.
Principal Scientist/Owner. HENNESSY CONSULTING LLC, Bellingham, Washington
March 2021 – February 2025.
Senior Environmental Scientist. FLOYD|SNIDER, Seattle, Washington
2001 – February 2021.
Managing Scientist. ANCHOR QEA, LLC. Seattle and Bellingham, Washington
1999 – 2001.
Senior Environmental Scientist. WINDWARD ENVIRONMENTAL, LLC., Seattle, Washington
1993 – 1999.
Environmental Scientist. EVS ENVIRONMENT CONSULTANTS, Seattle, Washington
Education
M.S., Fisheries Science, University of Washington, 1998
B.S., Environmental Science, Western Washington University, 1992
B.A., Social Science, University of California, Irvine, 1990
Publications and Presentations
Hennessy, D.P. 2023. Stream Macroinvertebrate Natural Variability and Responses to Anthropogenic Stress. Annual Meeting of Pacific Northwest Society of Environmental Toxicology and Chemistry. Gresham, Oregon.
Hennessy, D.P., D. Haury, L. Logan, J. Volosin, and S. Schroder. 2019. The Development of Porewater-Based Sediment Remediation Goals for a Complex Urban Waterway Using Regional Reference Area Toxicity Thresholds. Session D8, Establishing Remediation Goals. Battelle Tenth International Conference on Remediation and Management of Contaminated Sediments. New Orleans, Louisiana.
Hennessy, D.P., J. Volosin, L. Logan, D. Haury, and D. Glaser, 2016. Resolving Sediment Toxicity for Ecological Risk Assessment at Complex Urban Waterways. National Meeting of the Society of Environmental Toxicology and Chemistry, Orlando, Florida.
Bay, S., R.K. Brodberg, D. Glaser, and D.P. Hennessy, 2013. Short Course, Risk Assessment Primer for Bioaccumulatives in Southern California Bight. Southern California Chapter of the Society of Environmental Toxicology and Chemistry. San Pedro, California.
Mebane, C.A., F.S. Dillon, and D.P. Hennessy, 2012. Acute toxicity of cadmium, lead, and zinc, and their mixtures to stream-resident fish and invertebrates. Environmental Toxicology and Chemistry 31(6):1334-1348. DOI:10.1002/etc.1820.
Hennessy, D.P., C. Patmont, J. Dunay, B. Howard, L. McKee, and A. Corp, 2010. Sediment Risk Assessment for Hydrocarbons at a Site on an Urban Lake: Bioassay and Chemistry Results Support a Porewater-Based Approach. National Meeting of the Society of Environmental Toxicology and Chemistry, Portland, Oregon.
Mebane, C.A., D.P. Hennessy, and F.S. Dillon, 2009. Incubating rainbow trout in soft water increased their later sensitivity to cadmium and zinc. Water Air Soil Pollut. 205:245-250. DOI:10.1007/s11270-009-0070-4.
Mebane, C.A., D.P. Hennessy, and F.S. Dillon, 2007. Developing acute-to-chronic toxicity ratios for lead, cadmium, and zinc using rainbow trout, a mayfly, and a midge. Water Air Soil Pollut. 188:41-66. DOI:10.1007/s11270-007-9524-8.
Mebane, C.A., D.P. Hennessy, and F.S. Dillon, 2002. Development of site-specific water quality criteria for lead in zinc in the upper reach of the South Fork Coeur d’Alene River, Idaho. National Meeting of the Society of Environmental Toxicology and Chemistry, Salt Lake City, Utah.