California's ongoing struggle with water scarcity has spurred significant investment in reservoirs and dam expansion, but a new report from the Center for Biological Diversity (CBD) highlights why these massive infrastructure projects may worsen the state's water and environmental crises.
The report, titled "Beneath the Surface," challenges the notion that reservoirs are a sustainable solution, arguing that their benefits are undermined by environmental and economic costs, especially as climate change intensifies.
Reservoirs, often considered carbon-neutral, are significant sources of greenhouse gas emissions, releasing more climate-warming gases annually than 300,000 gas-powered cars, according to the report.
These emissions stem from multiple stages of a reservoir's life cycle, including construction, operation and microbial activity in sediments that accumulate in them.
"Building new, expensive reservoirs won't solve California's water supply problems but will actually make things worse," Sofia Prado-Irwin, a staff scientist at the CBD and lead author of the report, said in a statement.
"As temperatures rise, these boondoggle projects will become less effective and they'll emit massive amounts of polluting gases, making it harder to reach our climate goals," she said.
Reservoirs also alter ecosystems, the report said, disrupting wildlife habitats and worsening water loss through evaporation. In some cases, up to 25 percent of a reservoir's water volume can be lost to evaporation, further diminishing their utility in a warming climate.
Excess nutrients in reservoirs often lead to harmful algal blooms, which can harm fish populations, contaminate drinking water supplies and increase maintenance costs.
The report comes as California plans to invest in three new reservoirs, the largest of which—the Sites Reservoir—is slated to cost over $4 billion.
The Sites project has faced intense legal scrutiny, with environmental groups, including the CBD, challenging its compliance with the California Environmental Quality Act.
However, courts have ruled in favor of the Sites Project Authority, affirming that the project meets environmental standards.
"We've taken every step necessary to meet or exceed the standards laid out in the state's comprehensive environmental law, and the Court of Appeal has confirmed that," Fritz Durst, chair of the Sites Project Authority, said in a statement at the time of the ruling in September.
"This is good news for Californians because we are now one critical step closer to breaking ground on this essential water supply project," he said.
Newsweek contacted the Sites Project via email for comment.
California Governor Gavin Newsom agrees that the reservoirs are needed in the state.
In a statement in June, Newsom said, "California needs more water storage, and we have no time to waste—projects like the Sites Reservoir will capture rain and snow runoff to supply millions of homes with clean drinking water."
Instead of reservoirs, the new report advocates a shift to more climate-resilient solutions.
These include flood plain restoration, which could support fish and bird habitats; improving water filtration; enhancing carbon sequestration; and the creation of "sponge cities" that capture stormwater in rain gardens and retention basins.
On a household scale, the CBD is pushing for residents to capture water in rain barrels or cisterns.
"It's time to move away from these outdated ideas and focus on floodplain restoration, water recycling and other climate-resilient measures that can truly secure our water supply for future generations," Prado-Irwin said.
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