California’s environment got a little help from humans this month when the destruction of The Benbow Dam began on Aug. 1.
Though seen as a sad day for many who used the Benbow Lake during its 50 years as a community swimming location, others view the demolition as a long-overdue return to a more natural setting for wildlife and humans.
“It’s not just threatened salmon who will benefit from the removal of this derelict dam,” said NOAA’s Leah Mahan who is heading up the project. “But our researchers recently found a Bald eagle family nearby who seem to be using a heritage nest in the area and they just had two eaglets this season.”
When the Habitat Conservation arm of the National Oceanic and Atmospheric Administration and their partners broke ground on the Benbow Dam removal, they began the second-largest dam removal in California. The Benbow Dam, on the South Fork of the Eel River had become not just a safety hazard, but a hinderance to the Coho, Chinook and Steelhead salmon who rely on the river as its habitat. Both Coho and Chinook are considered federally-listed threatened species. They also began what some environmentalist see as a model for future dam demolition, especially the larger ones.
“Dams have mostly proven themselves to be not so cost efficient in the long run,” said Scott Greacen, executive director of Friends of the Eel River. “And this dam is no exception to that rule.”
Greacen said that while the Benbow Dam removal is not part of the multi-agency project known as the Eel River Action Plan, it will likely serve as an example of what the larger project can expect as the Potter Valley Project moves along.
“This dam couldn’t have stayed,” said Mahan. “It was too expensive to keep up and was causing an increasing amount of issues for anyone coming to experience this part of the Eel River.”
Greacan agreed, “It was scary especially for anyone trying to kayak or canoe on that part of the river, it had become a major liability and was getting worse.”
Mahan explained that in addition to the eagle family nearby her project team have witnessed River otters, Mountain lions, Yellow-Legged frogs and most recently, a bear right on the river edge, to name on a few wild animals who depend on the river. She hopes that the dam’s removal will allow those wildlife a safe place to thrive, while opening up new recreational opportunities for people to enjoy the Benbow Lake area again.
When the dam was built in the 1930s, water built up behind it, forming a 123-acre lake. The lake has been used for swimming and boating, and was also a tourist attraction for the past 50 years.
However, the dam limits access to upstream habitat during the winter. It also prevents water, sediment, and wood (from trees) from flowing downstream naturally. This lack of natural flow has reduced the quality of habitat near the dam.
Before the dam was built, roughly 20,000 Chinook and as many as 17,000 coho salmon swam past the dam site. In 2010, there were only 1,000 Chinook and 500 coho in this part of the Eel River.
The banks of the lake have eroded due to the unnatural wave action caused by the lake and sediment accumulation upstream of the dam. The lake is surrounded by redwood trees, but erosion is causing the banks to be unstable, and they are toppling over. The dam itself is in poor repair and could become a liability.
NOAA Fisheries, along with the California Department Parks and Recreation began removing the dam last week. The project will improve passage to nearly 50 miles of high-quality spawning and rearing habitat, assisting with the recovery of salmon and steelhead. The removal will improve habitat in the former lake area too. The California Conservation Corps will be planting native vegetation along the banks, along with other measures, to help control erosion.
Once natural flow has returned to the area, Mahan said she will monitor where natural pools begin to appear and hopes to make proposals in the coming years for development of pool enhancement.
“We want to see people enjoying the Benbow Lake again,” Mahan said. “We hope that this work allows for people, wildlife and fish to all be able to the return to this area and to enjoy it for hundreds of years after.”
To follow the project, visit www.habitat.noaa.gov. Mahan said that the project is aiming to be complete by October 15, with the possibility of extensions to October 30.