Alaska encompasses an area of about 365 million acres—more than the combined area of the next three largest states of Texas, California, and Montana. The state is bound on three sides by water, and its coastline, which stretches about 6,600 miles (excluding island shorelines, bays and fjords) and accounts for more than half of the entire U.S. coastline, varies from rocky shores, sandy beaches, and high cliffs to river deltas, mud flats, and barrier islands. The coastline constantly changes through wave action, ocean currents, storms, and river deposits and is subject to periodic, yet often severe, erosion. Alaska also has more than 12,000 rivers, including three of the ten largest in the country: the Yukon, Kuskokwim, and Copper Rivers. (See fig. 1.) While these and other rivers provide food, transportation, and recreation for people, as well as habitat for fish and wildlife, their waters also shape the landscape. In particular, ice jams on rivers and flooding of riverbanks during spring breakup change the contour of valleys, wetlands, and human settlements. Permafrost (permanently frozen subsoil) is found over approximately 80 percent of Alaska. It is deepest and most extensive on the Arctic Coastal Plain and decreases in depth further south, eventually becoming discontinuous. In northern Alaska, where the permafrost is virtually everywhere, most buildings are elevated to minimize the amount of heat transferred to the ground to avoid melting the permafrost. However, rising temperatures in recent years have led to widespread thawing of the permafrost, causing serious damage. As permafrost melts, land slumps and erodes, buildings and runways sink, and bulk fuel tank areas are threatened. (See fig. 2.) Rising temperatures have also affected the thickness, extent, and duration of sea ice that forms along the western and northern coasts. Loss of sea ice leaves coasts more vulnerable to waves, storm surges, and erosion. When combined with the thawing of permafrost along the coast, loss of sea ice seriously threatens coastal Alaska Native villages. Furthermore, loss of sea ice alters the habitat and accessibility of many of the marine mammals that Alaska Natives depend upon for subsistence. As the ice melts or moves away early, walruses, seals, and polar bears move with it, taking themselves too far away to be hunted. Federal, state, and local government agencies share responsibility for controlling and responding to flooding and erosion. The U.S. Army Corps of Engineers has responsibility for planning and constructing streambank and shoreline erosion protection and flood control structures under a specific set of requirements. The Department of Agriculture’s Natural Resources Conservation Service (NRCS) is responsible for protecting small watersheds. The Continuing Authorities Program, administered by the Corps, and the Watershed Protection and Flood Prevention Program, administered by NRCS, are the principal programs available to prevent flooding and control erosion. Table 1 below lists and describes the five authorities under the Corps’ Continuing Authorities Program that address flooding and erosion, while table 2 identifies the main NRCS programs that provide assistance for flooding and erosion. In addition to the Corps’ Continuing Authorities Program, other Corps authorities that may address problems related to flooding and erosion include the following: Section 22 of the Water Resources Development Act of 1974, which provides authority for the Corps to assist states in the preparation of comprehensive plans for the development, utilization, and conservation of water and related resources of drainage basins. Section 206 of the Flood Control Act of 1960, which allows the Corps’ Flood Plain Management Services’ Program to provide states and local governments technical services and planning guidance that is needed to support effective flood plain management. A number of other federal agencies, such as the Departments of Transportation, Homeland Security (Federal Emergency Management Agency), and Housing and Urban Development, also have programs that can assist Alaska Native villages in responding to the consequences of flooding by funding tasks such as moving homes, repairing roads and boardwalks, or rebuilding airport runways. In additional to government agencies, the Denali Commission, created by Congress in 1998, while not directly responsible for responding to flooding and erosion, is charged with addressing crucial needs of rural Alaska communities, particularly isolated Alaska Native villages. On the state side, Alaska’s Division of Emergency Services responds to state disaster declarations dealing with flooding and erosion when local communities request assistance. The Alaska Department of Community and Economic Development helps communities reduce losses and damage from flooding and erosion. The Alaska Department of Transportation and Public Facilities funds work to protect runways from erosion. Local governments such as the North Slope Borough have also funded erosion control and flood protection projects. Flooding and erosion affects 184 out of 213, or 86 percent, of Alaska Native villages to some extent, according to studies and information provided to us by federal and Alaska state officials. The 184 affected villages consist of coastal and river villages throughout the state. (See fig. 3.) Villages on the coast are affected by flooding and erosion from the sea. For example, when these villages are not protected by sea ice, they are at risk of flooding and erosion from storm surges. In the case of Kivalina, the community has experienced frequent erosion from sea storms, particularly in late summer or fall. These storms can result in a sea level rise of 10 feet or more, and when combined with high tide, the storm surge becomes even greater and can be accompanied by waves containing ice. Communities in low-lying areas along riverbanks or in river deltas are susceptible to flooding and erosion caused by ice jams, snow and glacial melts, rising sea levels and heavy rainfall. Flooding and erosion are long-standing problems in Alaska. In Bethel, Unalakleet, and Shishmaref for example, these problems have been well documented dating back to the 1930s, 1940s, and 1950s, respectively. The state has made several efforts to identify communities affected by flooding and erosion over the past 30 years. In 1982, a state contractor developed a list of Alaska communities affected by flooding and erosion. This list identified 169 of the 213 Alaska Native villages, virtually the same villages identified by federal and state officials that we consulted in 2003. In addition, the state appointed an Erosion Control Task Force in 1983 to investigate and inventory potential erosion problems and to prioritize erosion sites by severity and need. In its January 1984 final report, the task force identified a total of 30 priority communities with erosion problems. Of these 30 communities, 28 are Alaska Native villages. Federal and state officials that we spoke with in 2003 also identified almost all of the Native communities given priority in the 1984 report as still needing assistance. While most Alaska Native villages are affected to some extent by flooding and erosion, quantifiable data are not available to fully assess the severity of the problem. Federal and Alaska state agency officials that we contacted could agree on which three or four villages experience the most flooding and erosion, but they could not rank flooding and erosion in the remaining villages by high, medium, or low severity. These agency officials said that determining the extent to which villages have been affected by flooding and erosion is difficult because Alaska has significant data gaps. These gaps occur because remote locations lack monitoring equipment. The officials noted that about 400 to 500 gauging stations would have to be added in Alaska to attain the same level of gauging as in the Pacific Northwest. While flooding and erosion has been documented in Alaska for decades, various studies and reports indicate that coastal villages in Alaska are becoming more susceptible. This increasing susceptibility is due in part to rising temperatures that cause protective shore ice to form later in the year, leaving the villages vulnerable to storms. According to the Alaska Climate Research Center, mean annual temperatures have risen for the period from 1971 to 2000, although changes varied from one climate zone to another and were dependent on the temperature station selected. For example, Barrow experienced an average temperature increase of 4.16 degrees Fahrenheit for the 30-year period from 1971 to 2000, while Bethel experienced an increase of 3.08 degrees Fahrenheit for the same time period. Alaska Native villages have difficulty qualifying for assistance under the key federal flooding and erosion programs, largely because of program requirements that the project costs not exceed economic benefits, or because of cost-sharing requirements. For example, according to the Corps’ guidelines for evaluating water resource projects, the Corps generally cannot undertake a project whose costs exceed its expected economic benefits as currently defined. With few exceptions, Alaska Native villages’ requests for the Corps’ assistance are denied because of the Corps’ determination that project costs outweigh the expected economic benefits. Alaska Native villages have difficulty meeting the cost/benefit requirement because many are not developed to the extent that the value of their infrastructure is high enough to equal the cost of a proposed erosion or flood control project. For example, the Alaska Native village of Kongiganak, with a population of about 360 people, experiences severe erosion from the Kongnignanohk River. However, the Corps decided not to fund an erosion project for this village because the cost of the project exceeded the expected benefits and because many of the structures threatened are private property, which are not eligible for protection under a Section 14 Emergency Streambank Protection project. Meeting the cost/benefit requirement is especially difficult for remote Alaska Native villages because the cost of construction is high—largely because labor, equipment, and materials have to be brought in from distant locations. Even villages that do meet the Corps’ cost/benefit criteria may still not receive assistance if they cannot provide or find sufficient funding to meet the cost-share requirements for the project. By law, the Corps generally requires local communities to fund between 25 and 50 percent of project planning and construction costs for flood prevention and erosion control projects.