A Changing Dam Landscape
Dams have been crucial to the development of modern society, providing benefits such as hydropower, flood control, water storage, and navigation. The U.S. has relied heavily on dam construction to provide electricity and water to growing cities. The 1800s and 1900s experienced a growth in dams as demand for water, electricity, and navigation increased and the U.S. became industrialized. An estimated 10,000 new dams were constructed between 1920 and 1950 and 40,000 between 1950 and 1980. However, despite the many benefits that dams have provided, it has become apparent that not all dams are completely beneficial, and that some structures have become obsolete and detrimental to the environment.
Of all the dams in the U.S., only 3% are hydroelectric dams, which supply less than 7% of the country’s demand for electricity. The majority of dams were built for flood control, navigation, and irrigation. In addition to the small contribution to the nation’s supply of renewable energy, dams obstruct natural hydrologic and biologic functions. Approximately 600,000 miles, or about 17% of rivers in the U.S. are impacted by dams, which block or alter historical natural flows. In California, dams obstruct the flow of water from inland areas to the Pacific Ocean as well as threaten migration of fish species such as the Southern California Steelhead Distinct Population Segment, a population segment of steelhead that is endangered due to habitat loss. In recent decades, a shift has occurred, with more dams being removed than constructed due to being obsolete, posing public hazards, or substantially impeding on ecological functions. Over the past 30 years, over 1,300 dams have been removed. 82 dams have been removed in 2018 alone, with 35 of those removals having occurred in California.
Aspen has recently played a role in investigating the current state of dam removals in the U.S. as part of the Rindge Dam Removal Pathway Risk-Benefit Assessment. Aspen’s work will assist the California Department of Parks and Recreation’s (DPR) decision-making process to remove Rindge Dam, an obsolete dam located in Malibu, California. Rindge Dam was completed in 1926 by a private landowner to provide irrigation and household water use, but within 20 years, it had completely filled with sediment and was decommissioned in 1967. DPR is assessing options to remove the dam to reopen prime habitat for the endangered steelhead in Malibu Creek. Aspen’s extensive research and surveys with dam removal project participants found dozens of dam removal projects within the past two decades that were completed to reconnect fragmented riverine habitat, restore sediment to depleted coastal habitats, improve water quality, and restore populations of endangered aquatic species. Noteworthy dam removal projects include the removal of Glines Canyon (210 feet tall), Elwha (105 feet tall), Condit (125 feet tall), and San Clemente (105 feet tall) dams, which were among the largest dams removed in the U.S. and the world. Removing Rindge Dam would require sufficient funds, public support, and strong leadership that is effective at navigating the regulatory aspects of the project and managing demolition activities. The list of dam removal projects and additional research on project partners and funding sources would assist DPR to plan the removal process for Rindge Dam.
Aspen is also assisting Ventura County with the removal of Matilija Dam on a tributary of the Ventura River. Aspen prepared an EIS/EIR for the original dam removal concept in 2004 and will be preparing a subsequent EIR for a revised dam removal scheme in 2020.