Sediment Studies Conclude that Dam Removal is Safe and Affordable
California coastal commission (CCC) analysis is most comprehensive study of sediment behind the dams to date.
After completing its sediment analysis, the California Coastal Conservancy wrote in a letter to the Federal Energy Regulatory Commission: “the Conservancy has concluded that removal of the four lowermost dams on the Klamath River, Iron Gate, Copco II, Copco I, and J.C. Boyle is feasible, affordable under a variety of scenarios, and necessary for the recovery of Pacific Salmon, a vitally important coastal resource of great interest to the Conservancy, to the State of California, to sovereign tribes, and to the nation.”Specific findings of the CCC include:
the toxicity of the sediment in the four lowermost reservoirs is low, and will not affect the method or cost of dam decommissioning;
downstream erosion of sediment is a feasible method of sediment management under a dam removal scenario;
less than four million cubic yards of fine sediment would erode downstream to the marine environment in the event of decommissioning;
the duration of sediment transport can be compressed to a period ranging from 1-4 months, thereby avoiding or diminishing adverse effects associated with substantial sediment transport;
sediment transport below Iron Gate, even under the most conservative estimates, would not cause flooding downstream.
Another study by Camp Dresser & McKee Inc.is often cited by dam removal critics. Referred to as the CDM Report, it suggests that the high cost of sediment removal would push dam removal into the billions of dollars. However, the CDM Study fails to acknowledge the results of many of the aforementioned studies. In addition the CDM report assumes that sediment removal will be mandated by the California North-coast Regional Water Quality Control Board because the Klamath is listed as "impaired" by sediment. According to Water Board staff, this is an unfounded assumption as exemptions for restoration activities are common-place.
- Downstream Sediment Deposition After Dam Removal -- Stillwater Sciences (May 2004)
- Reservoir Sediment Sampling Plan -- Gathard Engineering (June 2006)
- Summary of Reservoir Sediment Analysis -- California Coastal Conservancy (Sept. 2006)
- Reservoir Sediment Analysis Results -- Gathard Engineering (Sept. 2006)
- Reservoir Sediment Toxicity Analysis Results -- Shannon and Wilson, Inc.(Sept. 2006)
- Update to Downstream Sediment Deposition Study -- Stillwater Sciences (Sept. 2006)
- Klamath River Dam Removal Study: Sediment Transport DREAM-1 Simulation -- Stillwater Sciences for California Coastal Conservancy (Oct. 2008)
- Memo Debunking Dioxin Concern in Klamath Sediments-- NOAA (Apr. 8, 2008)
- Effects of Sediment Release Following Dam Removal on the Aquatic Biota of the Klamath River -- Stillwater Sciences for California Coastal Conservancy (Jan. 2009)
(Thanks to American Rivers for providing links!)