Hazards
Landslides and their effects on salmon habitat at Hanford Reach National Monument and vicinity, southeastern Washington
Landslides constitute a major geologic hazard because they are widespread, occurring in all 50 states, and cause $1-2 billion in damages and more than 25 fatalities on average each year. Landslides pose serious threats to highways and structures that support fisheries, tourism, timber harvesting, mining, and energy production as well as general transportation. Landslides commonly occur with other major natural disasters such as earthquakes and floods that exacerbate relief and reconstruction efforts. Expanded development and other land use have increased the incidence of landslide disasters.
The enormous damages from landslides can be reduced. The primary objective of the Landslide Hazards Program is to reduce long-term losses from these hazards by improving our understanding of the causes of ground failure and suggesting mitigation strategies. Our investigations are conducted in partnership with Federal, State, and local agencies.
White Bluffs of the Columbia River at Hanford Reach National Monument are susceptible to landslides that may cause significant harm to spawning and rearing habitat of the fall chinook salmon.
The Hanford Reach National Monument is the only USFWS national monument. Designated a national monument in 2000, it is a recent addition to USFWS's land-management responsibilities. Several jurisdictions take part in administering specific aspects of the unit. These agencies, with the USFWS, are beginning the planning process for this new monument.
One of the biggest problems facing the Hanford Reach is irrigation-induced landslides on the White Bluffs along the Columbia River. The landslides have been occurring since the late 1960s and have caused serious concerns. Landslide debris entering the Hanford Reach of the Columbia River may seriously harm spawning and rearing habitat of the fall chinook salmon and, indirectly, damage cultural heritage resources of the Monument. One landslide partially blocked the river and caused increased erosion of Locke Island. The increased erosion damaged cultural heritage resources on the island.
Between 40,000 and 80,000 fall chinook salmon annually return to spawn in Hanford Reach. Hanford Reach has one of the largest and healthiest salmon populations in the Columbia River basin. Fifteen to thirty million fry are produced annually, which contributes to commercial, sport, and tribal fisheries.
The Hanford Reach National Monument Federal Planning Advisory Committee commissioned an assessment of the White Bluffs landslides. The report, completed in April 2003 by Triangle Associates, recommended a systematic, detailed study of the landslides prior to determining remedial actions, which potentially will be very costly.
In response to the recent assessment, USFWS requested the USGS submit a research plan aimed at providing the information needed to help determine the most effective remedial strategies. The resulting USGS proposal was submitted to the USFWS. It is a five-year program that is multidisciplinary in focus, relying on geologic understanding of landslides and hydrologic and biologic expertise. Research will start in fiscal year 2005, if funding becomes available.
