The state of California is revising its strategy to prevent the spread of golden mussels into Lake Orovilleone of the state’s most significant reservoirs. This shift comes after a newly commissioned risk assessment suggested that the invasive species poses a lower threat to the lake than initially anticipated. While no mussels have been found in Lake Oroville yet, experts are divided on the effectiveness of the revised approach.
The decision to scale back protections follows the discovery of golden mussels in the Sacramento-San Joaquin River Delta in, marking their first detection in North America. These mussels are known for their rapid spread and ability to encrust surfaces, which can disrupt water supplies and damage infrastructure such as dams and power plants. The Delta’s critical infrastructure, including pumps and canals, has become a conduit for the larvae to spread downstream.
Revised protection measures for Lake Oroville
In response to the new risk assessment, the Department of Water Resources has decided to end the boat inspection and decontamination program for Lake Oroville and nearby reservoirs, including the Thermalito Forebay and Thermalito Afterbay. This program, which cost approximately $7.5 million to initiate and $6.5 million annually to maintain, was deemed too costly and potentially ineffective given the natural flow of river water into the reservoir. Instead, the department will focus on installing UV treatment systems in downstream power plants, a measure estimated to cost around $1 million.
Tanya Veldhuizen, special projects section manager in the Department of Water Resources’ environmental assessment branch, explained that the decision was influenced by the unique conditions of Lake Oroville. The assessment found that while surface temperatures are suitable for mussel survival, the deeper waters are too cold for reproduction. Additionally, the lake’s low nutrient levels and fluctuating water levels make it less hospitable for mussels to establish nuisance populations.
Expert opinions on the revised strategy
Invasive species experts have mixed opinions on the revised strategy. Anthony Ricciardi, a professor of biology and director of the Bieler School of Environment at McGill Universityemphasized the importance of controlling key hubs to prevent the spread of invasive species. He warned that boats and aquatic weeds could still transport mussels to Lake Oroville and other water bodies, posing a significant risk.
Demetrio Boltovskoy, a retired researcher from Argentina’s National Scientific and Technical Research Council, noted that while precautionary measures can delay the spread of invasive species, it is ultimately unavoidable. He suggested that reducing precautions may be reasonable given the challenges of completely stopping the mussels’ range expansion.
However, Martha Volkoff, environmental program manager for the California Department of Fish and Wildlife‘s Invasive Species Program, argued that delaying invasions can result in long-term savings. She emphasized the importance of continued efforts to protect California’s waterways from invasive species.
Shifting responsibility to boaters
With the end of the boat inspection program, the responsibility for preventing the spread of golden mussels now lies more heavily with boaters. The Department of Water Resources is urging boaters to ensure their vessels are clean, drained, and dry, especially when leaving infested bodies of water like the Delta. If mussels are detected in Lake Oroville, the department will reinstate boat inspections as they leave the lake, a strategy already in use at other infested lakes such as Castaic and Pyramid.
Managers of other Northern California lakes, including FolsomTahoeand Berryessahave indicated that they will continue their inspection programs. Drew Gantner, manager of water resources at the Solano County Water Agencyexpressed concern that the decision to scale back protections at Lake Oroville could increase the risk of mussel infestations in other water bodies.
As California grapples with the challenges posed by golden mussels, the revised strategy for Lake Oroville highlights the complex balancing act between cost, effectiveness, and the long-term protection of the state’s vital water resources.
