On Thursday, PG&E’s 50-year license for the Eel River Dams expired, with the company opting against renewing the costly Potter Valley Project (PVP). After the license is surrendered and the project is decommissioned, the long road to removing the Eel River Dams will begin, eventually creating California’s longest free-flowing river.
The PVP is a hydroelectric system consisting of two dams, a diversion tunnel and a powerhouse on the Eel River. When old dams come due for relicensing, they are required to meet 21st century standards for fish passage. Upgrading these ancient structures comes with enormous cost, so much so that it is often cheaper to just remove the dams entirely. That’s why PG&E has opted to abandon the outdated structures.
The Scott Dam, siting at 99-years-old, was built as part of the PVP to provide hydroelectric power for the city of Ukiah. Before the dam was installed, the Eel hosted some of the most dramatic salmon and steelhead runs in California. The few remaining fish are now listed as threatened under the Federal Endangered Species Act. Because the dam prevents the normal, seasonal flushing of sediments in the river, the water is considered “impaired” under the Clean Water Act.
According to CalTrout, “The Eel represents perhaps the greatest opportunity in California to restore a watershed to its former abundance of wild salmonids.”
Over the coming months, the Federal Energy Regulatory Commission will ask PG&E to prepare a process to surrender their license and decommission the project. The decommissioning process will likely take years, mostly due to the environmental and economic impact. A significant amount of Eel River water is piped over to the Russian River where farmers and winemakers depend on these flows. Due to looming drought scenarios, the dam removal will likely include agreements to compensate agricultural interests when there is not enough water to meet their needs.
The Eel River Dam removal project will take place after the removal of the four Klamath River dams, which is set to occur later this year.
The Science Behind Dams
There are well over 1,000 dams in California, some more than a century old. Most dams were erected to establish critical water supply, but also for hydroelectric power generation and flood control. If Shasta and Keswick Dams in Shasta County were removed, towns like Redding could literally be washed away during spring flooding season. But there are still plenty of old dams, structures that no longer serve their original purposes, that could be removed to give wild salmon and steelhead access to ancestral spawning habitat.
Dams degrade water quality. They also block the rich nutrients brought into the habitat by spawning anadromous fish. The salmon and steelhead using our rivers for spawning have traveled and fed in thousands of miles of ocean water from as far away as Canada, Alaska or even Russia. When they die after spawning these exotic nutrients supercharge the ecosystem benefiting all forms of life. The reservoirs behind dams warm and broaden the river corridor often providing warm water habitat for destructive non-native species. Even though many dams provide fish ladders allowing passage over the dams, they are largely statistical failures. For reasons known only to the fish, many fish will not use them. This creates a large pod of fish below the dams that will never spawn. The dams also give piscivorous species (fish that eat other fish) like pikeminnows a terrific opportunity to dine on salmon and steelhead smolts that will never make it to the ocean.
Dam removal is about much more than restoring endangered fish populations. If you consider the fact that everything in an ecosystem is connected, you realize you cannot alter one aspect of a river without impacting everything else. Once streams are returned to their natural states, they are able to cleanse themselves, wash out all the sediments that smother aquatic plants, insects and fish. Improved water quality also impacts everything from associated wetlands (and the life sustained there) to coastal beaches and estuaries.
So, you think California has a dam problem? We are far from alone. According the the US Army Corps of Engineers, there are over 80,000 dams three feet or greater in this country. California is on the cutting edge of a national movement for dam removal where the benefits outweigh the costs for retrofitting century-old structures built in an age where we thought we had an endless supply of good habitat.
As communities strive to wrestle with all of the complex economic and environmental hurdles involved in dam removal, more are deciding the benefits outweigh the costs. Not all dams are good candidates for removal, but enough of them are to feed a growing national movement to come up with win-win scenarios for fish, ecosystems and human beings. It’s nearly everyone’s dam business.