| Audubon Society of the District of Columbia: Field trips, events, birding around D.C., Logan Meadow sanctuary and newsletter articles. |
| Biodiversity Database of the Washington, D.C., Area: Searchable database of information and images. Includes organisms and regional nature and preservation areas in the D.C. area. |
| Capital River Relief: Coaltion of organizations and individuals focused on cleaning up the Anacostia and Potomac Rivers. Features cleanup schedule, photo gallery, press kit, and FAQs. |
| Casey Trees Endowment Fund: A project to restore the tree canopy of Washington, DC, administered by the Garden Clubs of America. Includes a review of the street tree inventory carried out in 2002. |
| DC Department of Health - Environmental Health Administration: Works to prevent and control environmentally related diseases while protecting and preserving the ecological system in the district. Features a guide to the bureaus and divisions that make up the Administration. |
| DC Energy Office: Promotes energy efficiency through conservation, education, and fuel assistance programs and by regulatory intervention. Includes consumer information, a description of agency programs, a guide to resources in its library, an events calendar, and links to related sites. |
| DC Greenworks: Non-profit organization supports projects and provides information on low-impact storm water management and urban forestry. Includes information on green roofs, rain gardens, and tree care. |
| Earthjustice - Washington DC: Focused on ensuring that national clean water and clean air standards are properly set and enforced in the District. Features urgent cases, opportunities for action, legislative information, news and campaigns. |
| Earthquake History of the District of Columbia: Seismic history of DC from the National Earthquake Information Center. |
| Environmentors: Committed to helping one hundred public high school students create opportunities for brighter futures through mentorship, educational enrichment, and the fostering of a sense of environmental stewardship. |
| Flora of the Washington-Baltimore Area: Offers information about flora native to the area. Includes a specimen database, projects, spring flowering records and a gallery. |
| Friends of the Earth DC Environmental Network: A consortium of conservation organizations that meets regularly to focus on environmental problems specific to the region, exchange information, and coordinate strategies. Includes background documents [PDF]. |
| Hardy Palm Trees and Ferns: Showcases plants that can survive the area's often snowy winters. |
| HowStuffWorks: Exploding Manholes: Information on the frequent mishaps under the streets of the city. |
| Maryland-National Capital Park and Planning Commission: Acquires, develops, maintains and administers a regional system of parks in Montgomery and Prince George's Counties in Maryland. |
| Pre-Columbian Society of Washington, DC: Promotes interest in Pre-Columbian cultures through annual symposia, monthly meetings, and a newsletter. Includes newsletter index. |
| Sustainable Washington Alliance: Network of individuals, businesses, and organizations working to create a sustainable future for the region. |
| The Nature Conservancy - Maryland/District of Columbia: Works to protect critical natural lands. Features places protected, events, news and volunteer opportunities. |
| Trash Force: Volunteer group that picks up trash and recyclables from public areas every other weekend. Features FAQ, news, awards, volunteer opportunities and articles. |
| Urban Land Institute: Non-profit research and education organization focusing on the use of land to enhance the environment. |
| Washington Regional Network for Livable Communities: Advocates "smart-growth" transportation investments, land use policies, and community designs. Includes newsletter archive and policy documents. |
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