protecting and restoring wetland habitats. All federal land in the Sierra Nevada complies with a 1990 Presidential Executive Order that mandates 'no net loss' of wetlands, and requires federal agencies to map and protect all existing wetlands. In 1996 the United States Fish and Wildlife Service delineated and classified some of the wetlands of the Sierra Nevada, including all of Yosemite National Park. This was performed through an analysis of aerial photographs and topographic maps, as a part of the National Wetlands Inventory Web Site (NWI). The NWI maps have not been rigorously ground-truthed and only delineate wetlands larger than in size. The National Park Service restores to natural conditions wetlands that have been drained or filled in the past. Most recently in Yosemite Valley, the Cook's Meadow restoration project involved filling old drainage ditches that were draining the meadow and removing an old roadbed that was inhibiting water flow. These actions are currently being monitored with vegetation transects and mapping of surface water to determine how successful the project was in restoring the wetland. References Further reading Storer, T. I., Usinger, R.L., and D. Lukas. 2004. Sierra Nevada Natural History. University of California Press, . Weeden, N.L. 1996. A Sierra Nevada Flora. Wilderness Press, . External links Sierra Nevada Forests images at bioimages.vanderbilt.edu (slow modem version) World Wildlife Fund Terrestrial Ecoregions - Sierra Nevada forests (NA0527) Plant communities of California Nearctic realm