Rankings: Companies are ranked below based on gross revenue they reported in 2001 for providing environmental services and products to domestic and international markets. The proportion of a firm’s gross environmental services revenue to its total gross revenue is provided as a percentage. Revenue figures are in $ millions. Percentages are rounded up or down to generate whole numbers.

Figures include revenue from all environmental subsidiaries unless otherwise noted. Category of non-U.S. represents revenue from environmental work performed outside the United States. Companies with subsidiaries included are designated by this symbol (†).

Type of Firm: Designations are based on the largest proportion of environmental revenue reported by firms in seven categories: DES=Design, consulting and/or studies; CON=Construction and/or remediation; PM=Project and/or program management; EQP=Equipment and/or product manufacture; R&D=Technology and/or research & development; LAB=Laboratory and/or analytical services; OPS=Contract operations; OTH=Services not included in the above categories. Two or more designations appear if the largest proportion of revenue is evenly split between two or more categories, or if these categories are within 5% of each other.

Markets: Markets are shown as a percentage of gross environmental revenue: HAZ WASTE= Chemical and industrial waste cleanup and/or material management; Lead and asbestos study, management and abatement; Municipal and other nonhazardous solid waste landfills and recycling facilities. NUCLEAR WASTE=Nuclear or radioactive materials and waste handling, storage and/or disposal. AIR=Facility air pollutant emissions study, management and control; WATER QUALITY= Industrial and/or municipal water system supply and treatment; WASTEWATER TREATMENT=Industrial and/or municipal wastewater treatment systems; ENVIRONMENTAL MANAGEMENT=Site assessments, audits, due diligence, compliance and environmental information technology management. ENVIRONMENTAL SCIENCES=Environmental impact statements (EIS/EIRs); natural resources, modeling, wetlands OTHER=Environmental markets not included above.

Clients: Work for types of clients is shown as a percentage of gross environmental revenue: PRIVATE=Private corporations; utilities, other; FEDERAL=Federal U.S. agencies and/or foreign governments; STATE/LOCAL=State and municipal entities. Markets and clients totals may not add up to 100%, because of rounding.

 An alphabetical list of the Top 500 is available by clicking here.