Who We Are

updated: 17-January-2007
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Our Approach

What We Do


Harwell Gentile & Associates, LC (HGA) was established in 1998 by Dr. Mark Harwell and Dr. Jack Gentile to coordinate their scientific consulting activities in support of federal and state government agencies as well as private institutions.  The principals and affiliates of Harwell Gentile & Associates, LC were university-based scientists with a long history of conducting interdisciplinary studies on ecological risk assessment, ecotoxicology, and ecosystem management for sustainability of the environment.  The focus of research by HGA principals and affiliates is on: assessing ecological risks from natural and anthropogenic stressors affecting ecosystems at a diversity of spatial, temporal, and institutional scale issues; developing truly innovative interdisciplinary approaches to managing ecosystems, involving physical, natural, and social scientists; and the development of policy-relevant models to support sound environmental decision-making.

Current research emphasizes:

The scientists affiliated with Harwell Gentile & Associates LC were leaders in the development of the US Environmental Protection Agency’s ecological risk assessment paradigm (Harwell and Gentile 1992; Gentile et al. 1993).  They led the US Man and the Biosphere Human-Dominated Systems core project that created ecosystem management principles and applied them to the restoration of the Everglades (Harwell and Long 1992; Harwell et al. 1996; Harwell 1997, 1998).  Drs. Gentile and Harwell also created a methodology for developing conceptual ecological models of coupled human-environmental systems (Gentile et al. 2001), and they facilitated conceptual models for the South Florida ecosystems, the Coeur d'Alene River basin (in support of the US Department of Justice for a major natural resource damage assessment case), and the Fire Island estuary and barrier island ecosystem (in support of the US Army Corps of Engineers).

HGA scientists were leaders in the US EPA Unfinished Business, Reducing Risk, and Integrated Risk Projects, all focused on developing approaches for assessing relative ecological risks (Harwell et al. 1992). They have worked closely with the US EPA in training EPA scientists and managers in cumulative risk assessment concepts and procedures (Gentile and Harwell 2001). In addition, HGA conducted risk assessment analyses for Florida Power & Light and New Brunswick Power in support of licensing the conversion of power plants in Florida and Canada from burning fuel oil to use of ORIMULSION™.

HGA principals developed a framework for assessing ecological significance (Gentile and Harwell 1998) and are now applying that framework to assess the present ecological significance in Prince William Sound from the 1989 Exxon Valdez oil spill.  HGA is also currently assisting the development of performance criteria for the federal-state South Florida Comprehensive Ecosystem Restoration Plan.


US Environmental Protection Agency

US Department of Justice

US Army Corps of Engineers

South Florida Water Management District

Florida Department of Environmental Protection

Florida Power and Light Corp.

Eastern Research Group, Inc.

Golder Associates, Inc.

BITOR America

ExxonMobil Inc.

NOAA Environmental Cooperative Science Center


© HGA, LC  2006-2007


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