They've come to California by plane, on foot, and over seas. But aquatic pests are no ordinary immigrants. Invasive marine and freshwater species that travel here from around the globe can degrade the environment and cost millions of dollars to the economy and to government agencies. KPCC's Molly Peterson explores how California is coping with aquatic invasive plants and animals. She begins with a battle against an invader at the state's border.
[Sound of small plane pilot, communicating with air traffic control]
Molly Peterson: The shadow of our propeller plane dances on rocks 12,000 feet below as we head east, toward the desert. In a seat opposite me is Bob Muir of the Metropolitan Water District. He points out the Colorado River Aqueduct.
Bob Muir: It looks like a little straw from here, but when you get down there, it's an expansive waterway.
Peterson: Sixty-three miles of the system delivering Southland water – about a fourth – is open. And vulnerable. Earlier this year, divers found the first invasive quagga mussels near the top of the system.
Muir: They did everything they could to keep them out of the Colorado River. And in January, we heard the news that they were found, indeed, in Lake Mead.
Peterson: Bad news. Quaggas and their cousins, zebra mussels, have already wreaked havoc in other parts of the United States. The federal Environmental Protection Agency estimates they've caused 750 million to a billion dollars of damage in the Great Lakes Region.
So the Metropolitan Water District's shut down big stretches of its aqueduct, Muir says, leaving the pests no water to breed in.
Muir: And we call that desiccation. We're drying out and effectively eliminating the larva. That has proven to be one of the most effective methods of controlling populations of quagga. And trying to keep them from investing your water system.
[Sound of plane landing, propellers slowing]
Peterson: At a pumping plant next to the river, water district divers sample the quaggas before they start eradicating them.
[Sound of divers dropping into opening near plant]
Diver: Go ahead and lower my scuba gear first.
Peterson: A crane lowers divers into a narrow opening alongside the pump station. One of the divers mouths the word "thousands" – the quaggas have spread.
[Sound of water district employees taking photos of quaggas]
Peterson: Microbiologist Ric De Leon says he's been dreading these pests as long as he's worked for the water district – 14 years. Now he must stop them from taking up residence on pumps and clogging pipes. One way to do that is physical: new walls to separate the reservoir from the intake valves.
Ric De Leon: We need to have this barrier that separates the water once it's at our intake, from the water that's on the outside of the river. So we can add chlorine, molluskicides, potentially use heat, to kill whatever mussels are on this side, and not have issues with a natural environment.
Peterson: What to use behind the barrier? De Leon says scientists are still figuring that part out. Maybe a combination of additives and heat will slow the quaggas, since they come from cold Ukrainian and Russian waters. De Leon says the water district will experiment as he and other scientists study where quaggas are thriving in the West.
De Leon: It's one of the areas where it's not clear, is how they're going to behave in an environment that maintains year round temperatures higher than the east coast, or in Europe where they first came from. So that's one of the first open questions.
Peterson: Quaggas probably traveled here in or on a cargo ship. What's certain is that they eat the microscopic plants that feed native animals – and they've been doing that since they jumped the Atlantic Ocean. Williams College marine biologist Jim Carlton says species have sailed the world's ocean to California for a long time.
Jim Carlton: There were probably earlier invasions with some of the Spanish era shipping, back to the 1500s, but nobody was here and it's hard to track some of those very early invasions. But with the arrival of the gold rush ships from all over the world, a steady influx began, and it never really has stopped.
Peterson: Trade routes helped make the West Coast's bioregion home to hundreds of invasive species. San Francisco-based marine biologist Andrew Cohen says it's impossible to measure the extent of their damage in dollars.
Andrew Cohen: These organisms are transformers of the environment when they come in. And they transform it in a wide variety of ways. Some of them directly affect human activities. Often in ways that we don't like. But they also transform the environment, in terms of its diversity and functioning and its aesthetic values and its cultural values, and once they change them there's usually no way of fixing it.
Peterson: For the first time, the state of California is working on a multi-agency plan to prevent and manage invasives. The Fish and Game Department's Susan Ellis says it's crucial work, but –
Susan Ellis: There's not specific money for any of the actions or tasks in the plan, or for the plan in general.
Peterson: The state spends most eradication money after the fact, Ellis says – usually to protect endangered and native species. While California can apply for federal money, there's not much available to the states.
Ellis: The average amount people got was $40,000.
Peterson: That means most state policies still kick in only where and when the problems do. At Malibu Creek, it's believed water quality monitors unknowingly tracked New Zealand Mud Snails into the watershed. Now those snails are crowding out insects that native animals up the food chain eat.
Miwa Tamanaha of the Santa Monica Bay Restoration Commission says it's tricky to persuade people to behave differently before something bad happens.
Miwa Tamanaha: The thing is, it's not a visual problem. Like, you don't come into Malibu Creek and see it the way you would see littler, or see a rusty car. But it's – people should understand that this is something that compromises and impacts some of the places that they really care about.
Peterson: Wildlife managers expect that this fall's state plan won't include much new funding. So they're left to hope that what they're doing now is enough.