After months of intense lobbying, California's local mosquito control districts have won a key battle against new federal regulations that districts contended slowed them in their fight against West Nile virus.
The victory came late last week as the State Water Resources Control Board lifted monitoring requirements that districts said hindered ground treatment of mosquitoes in the larval stage.
While the new rules aimed to curb pesticide use on the ground, some mosquito districts responded by taking to the air, ordering aerial and truck-mounted sprayings far earlier and more frequently than in any year since the West Nile virus surfaced in California in 1999.
Even as they sprayed from above, mosquito districts warned that airborne tactics would result in widespread drift of potent pesticides, and that their inability to apply ground treatments posed a hazard to human health.
According to the federal Centers for Disease Control and Prevention, quashing mosquitoes before they hatch into flying adults is the safest, most effective method of curbing the spread of West Nile virus, a potentially fatal virus typically marked in humans by fever, body aches, headaches and swollen glands.
"We are really grateful that the state water board removed the larvicide monitoring requirements," said Catherine Smith, executive director of the Mosquito and Vector Control Association of California. "Our members are thrilled. This allows their technicians to reach more ground sites."
The new regulations were imposed after a federal court ruled in 2009 that the pesticide discharges from mosquito districts fell under the Clean Water Act because they threatened to pollute water. In response, the state water board, which oversees the act in California, began developing rules in concert with the mission of mosquito districts.
This posed a challenge for both entities, which for years clashed over finessing permit rules that would accommodate the public service performed by mosquito districts.
It seemed a classic California conflict: The state with the first and strongest clean water protections of any in the nation balancing those environmental concerns against the threat of a virus that has been a growing concern in the Sacramento region since 2005, when the area became ground zero for risk of infection.
That year, California led the nation in human cases of the disease with 935 reported cases, including 177 in Sacramento County. Nineteen California residents died of the virus in 2005.
So far this year, only three confirmed cases of West Nile virus have surfaced, in Modesto, Clovis and Kern County. None has been fatal.
The latest dust-up between the state water board and mosquito districts involved the monitoring requirements for ground treatments. Among other things, permit rules required monitoring sites before, the day of, and days after the application of larvicide.
Capping a years-long lobbying effort on behalf of its members, the statewide association rallied mosquito districts to back a series of strongly worded letters urging changes in the regulations.
Mosquito district officials contended the initial permit requirements were so onerous they prevented technicians from waging a timely ground war on larvae. That meant that each technician in California's more than 60 mosquito districts lost nearly 10 hours, and the ability to reach 50 more ground sites monthly, to monitoring and reporting requirements, Smith wrote in a June 27 letter to the water board.
Smith went on to say that the alternative was districts having to battle adult mosquitoes in flight, a less-effective – and more toxic – tactic that requires aerial spraying and truck-mounted fog spraying of adulticides.
The Sacramento-Yolo Mosquito and Vector Control District, for example, ordered aerial spraying on upward of 100,000 acres with adulticide on four separate days so far this season. This compares to 33,000 acres last year, and about 70,000 acres in 2010.
The virus has been found this year in a high number of dead birds in the Sacramento-Yolo region and an increasing number of mosquito samples.
In Placer County, only one dead bird with West Nile virus has been detected, along with five mosquito samples, officials said.
Still, the Placer County Mosquito and Vector Control District said it is pursuing a multi-pronged approach to prevention – relying heavily on the preferred method of going after larval pools.
"We're very pleased that we can now reach more spots by not having to go through the regulatory steps," said Joel Buettner, general manager of the Placer mosquito control district. "Timing is everything in trying to halt the mosquito life cycle."
For their part, water board officials said that all along they've been trying to smooth the way for the mosquito districts to do their jobs.
"Our goal is to protect water quality and part of that is to protect public health," said Jon Bishop, chief deputy director of the state water board. "We have been working with mosquito-vector control folks for a long time on this issue. We're not interested in making it harder for them."