California is known for many things, among them its spectacular landscapes, its extensive and productive agriculture, and its biodiversity. It is also a state in which the population is expected to grow by another 12 million people during the next 20 years. How the state preserves its quality of life in light of such pressures presents some challenges, especially for land use planners and natural resource managers.

Helping meet those challenges is the California Resources Agency, whose mission is "to restore, protect, and manage the state's natural, historical, and cultural resources for current and future generations using creative approaches and solutions based on science, collaboration, and respect for all the communities and interests involved."

The Resources Agency has developed a unique, Web-based tool to help fulfill that mission. It is one component of the agency's California Legacy Project, a six-year conservation effort focused on some key questions related to land conservation and planning issues:

• How can we identify and protect enough open land
• How and where will we set aside the land for urban green spaces to make neighborhoods attractive and provide recreation and refreshment?
• How can we create or restore crucial habitat and the linkages that biologists tell us are needed for all kinds of plant and animal species to survive?
• How can we keep farms, forests, and rangelands working and provide landowners with the tools to improve their stewardship practices?

To help land use planners and natural resource managers as they seek the answers to these and other questions, the California Legacy Project and Esri Professional Services have collaborated on the design and implementation of the digital atlas. The agency selected Esri Professional Services for this project because of Esri's background in natural resource management and Web site design. The result, the California Digital Conservation Atlas (www.legacy.ca.gov/new_atlas), is an ArcIMS 4 implementation that allows users to easily view, explore, and download natural resource and conservation data.

The data in the atlas is from a variety of sources—some public; some private; and some, such as the 20- and 50-year growth projections, the result of research done specifically for the atlas (metadata is provided for each data set). Some data categories—Conservation Related, Hydrology, Transportation, Land Ownership and Use, Political Boundaries, and Imagery Map Grids—serve as reference data and appear consistently in the table of contents. Other data categories-Terrestrial Biodiversity, Urban Open Space and Rural Recreation, Working Landscapes, and Stressors—are intended for particular types of analysis and, when selected, are mutually exclusive.

Each data category has subcategories; the more detailed the data, the better the support for decision makers. For example, the subcategories under Land Ownership and Use include

• Public and Conservation Lands (Bureau of Land Management, Department of Defense, etc.)
• State and Federal Easements (Easement, Easement, etc.)
• California Easement Areas
• County Generalized Plans (Agriculture and Grazing, High Density Commercial, etc.)
• Urbanized Areas
• Growth Projections 20 Year
• Growth Projections 50 Year

The 50-year growth projection for the coast of Southern California shows a solid mass of urban development from Los Angeles to San Diego except for a block of natural vegetation on the coast of northern San Diego County where the Camp Pendleton Marine Corps base is located. This population projection, and the population projections for the rest of the state, shows both the importance of the atlas and the urgency of better planning and natural resource conservation. As Madelyn Glickfeld, the California Legacy Project's director, notes, "Now is a crucial time for conservation decisions and investments. In 20 years, if we haven't done a good job of addressing the challenges of growth, the windows of opportunity will have slammed shut and we will be left with simply mitigating and reacting to resource impacts."

More broadly, the California Legacy Project and the California Digital Conservation Atlas demonstrate what can be achieved through the marriage of science and technology and the cooperation of individuals, private firms such as Esri, and public agencies. As Mary Nichols, California's secretary for resources, says, "The Digital Atlas is a treasure trove of tools and information for planners and the general public. Here, on a Web site open to all, are the facts and maps we need to chart a course for the future of California's magnificent natural legacy."

For further information about the California Legacy Project or the California Digital Conservation Atlas, contact Michael Byrne, California Water Resources Agency (tel.: 916-651-7592, e-mail: michael.byrne@resources.ca.gov), or Gerco Hoogeweg, Esri (tel.: 909-793-2853, ext. 1-1972; e-mail: ghoogeweg@esri.com) or visit the atlas (www.legacy.ca.gov/new_atlas).