Skyrocketing boat sales have filled lakes across Arizona with millions of dollars’ worth of new watercraft, potentially renewing the threat from quagga mussels, an invasive aquatic species that still lurks in waterways across the West. The tiny mollusks wreak havoc in reservoirs and other facilities and often move from lake to lake by clinging to the hulls of boats. Though extreme heat across the Southwest is helping cull portions of the population, officials fear the influx of new boat owners could raise the risk of another infestation. The mussels have spent more than a decade infiltrating water systems in nearly half of the state’s largest reservoirs, including Lakes Powell, Mead, Mohave, Pleasant and Havasu. The mussels, which reproduce quickly and in mass, can attach themselves to boat hulls, pipes, dam gates and other watercraft equipment. When moved to a new location they threaten the balance of life within a lake or reservoir. “Quagga mussels disturb the balance of the aquatic ecosystem,” said Kate Steighler, an aquatic invasive species coordinator at the Arizona Game and Fish Department. “They really affect plankton populations, which is the foundation of the food web. If you change that base, it can have several unforeseen circumstances.” A public awareness campaign paired with extensive decontamination regulations have resulted in five years without a recorded case of a new mussel infestation in Arizona. “Every boater needs to care because any of them could potentially be carrying these mussels into another water body,” Steighler said. “If you don’t care about aquatic species, then you should still care because the damage these mussels cause will hit you in your wallet.”
Worries about watercraft Recreational watercraft sales have been steadily rising in Arizona over the last eight years, which, according to data from the National Marine Manufacturers Association, is in keeping with national trends. Over the last five years, Arizonans have spent more than $960 million on watercraft. Approximately a fourth of that sum, $228 million, was spent last year. The most common sales are personal watercraft and freshwater fishing boats. This year’s data won’t be finalized until January, but based on this summer, John-Michael Donahue, communications director at the association, expects national and state sales to rise. In May, power boat sales in the U.S. rose by nearly 60%. Donahue said the last time a single month recorded such strong sales was in 2007. “The strong surge in summer boat sales underscores a heightened interest in boating as a way to enjoy the summer with loved ones while staying close to home,” Donahue said. “Especially as summer camps, sports leagues, and vacations have been canceled amid the pandemic.” As new boaters take to the waters, Steighler said it would take just a few inexperienced owners to accidentally start a new mussel infestation by incorrectly decontaminating a watercraft. “New boaters will be concerned with operating their boats and trailing them. They are more concerned with having fun, which is awesome, but they still need to be concerned with cleaning, draining and drying their watercraft,” Steighler said. “Everyone needs to get into this habit.” Decontamination is required for all watercraft used on bodies of water suspected or confirmed to contain aquatic invasive species. Failing to do so could result in a hefty fine. A notice of public information from the game and fish department lists over 50 bodies of water in nine counties that require decontamination. Nearly 35% of those lakes, rivers, streams, reservoirs and canals are home to quagga mussels. To mitigate the threat of watercraft transporting mussels between lakes, Steighler oversees the department’s stationary decontamination unit in Lake Havasu and its fleet of mobile units.
“The decontamination process for boats depends on how long they’ve been in the water," Steighler said. "The longer in the water the more thorough we need to be. Theoretically, it could take just one boat to start a new quagga infestation.” Alamo, Bartlett and Roosevelt lakes are the three bodies of water on the department’s priority list to keep mussel-free. This is based on the three reservoirs’ proximity to infested waters. Department data shows the annual number of watercraft decontaminations steadily rising each year, from 46 in 2015 to 285 in 2019. As of this August, the department had already recorded just over 250 decontaminations for the year. Based on last year, which showed 105 decontaminations in the final four months of 2019, Steighler predicts 2020 decontaminations will break the record yet again. Boaters can register online to have their watercraft inspected and serviced for free. Expenses are covered through watercraft registration funds. Woods to Water Wildlife Solutions has been contracting decontamination services with the department for the last four years. It’s one of about 20 companies in the state certified by the state to conduct this service. “It’s not only the law, it’s the responsible thing to do. It’s just a part of being a boat owner. Actually, it’s one of the only free parts of being a boat owner,” said Clint Luedtke, owner of Woods to Water. Depending on a watercraft’s size, anatomy and length of time in the water, Luedtke said the decontamination process can range from 30 minutes to 24 hours. “No two boats are the same and timing varies depending on whether it’s a fishing boat or a houseboat,” Luedtke said. “We’ve got to be sure we spray, scrape and clean every surface because you can’t let a single mussel through.” One of the most effective aspects of the process is the use of scalding water. Luedtke abides by industry standards and sprays every surface of the boat for 10 seconds with 140-degree water. Quagga mussels inherently don’t do as well in warmer water temperatures, which has been a way Arizona’s climate has been naturally reducing the invasive species population. 5/12/2021 Influx of new boats could spread destructive quagga mussels https://www.azcentral.com/story/news/local/arizona-environment/2020/09/07/influx-new-boats-could-spread-destructive-quagga-mussels/5688432002/ 4/5 Warmer waters Water temperatures in Arizona aren’t hot enough to drive the mussels into extinction, but they can contribute to less food and oxygen in the aquatic ecosystem, which often leads to die-offs. “High water temperatures do affect where mussels will thrive,” Steighler said. “Any animal will do better when they are within their optimum temperature range. When you get towards either end of the temperature tolerance, there is less survivorship.” The optimal temperature to kill young quaggas, also known as glochidia, is 95 degrees, according to Steighler, though the heat needed to kill adult mussels is far hotter. “Mussels have a really high thermal tolerance, but if temperatures get extreme enough that food availability and oxygen levels drop, it can lead to a die-off,” said Meg Duhr, a research outreach specialist at the Minnesota Aquatic Invasive Species Research Center. “But even when there is a die-off, it’ll never be enough to kill all of them.” A big bill The continuing statewide effort to keep these mussels at bay costs millions of dollars. Next year’s pending budget for the U.S. Bureau of Reclamation, which oversees water resource management, proposes spending $7.8 million to “combat and prevent the spread of invasive species.” The bureau is proposing that more than 70% of that money is spent on the “prevention, early detection and monitoring, containment and control of quagga and zebra mussels at existing facilities.” “The damage these mussels cause in water facilities keeps adding up, but we always have to have it as a goal to prevent them from spreading elsewhere” said Jeff McPherson, an aquatic ecologist for the bureau. “It takes millions to counter the impacts of these mussels, especially when they damage water facilities.” The Central Arizona Project, one of the state’s largest water suppliers, has spent an abundant amount of time and resources fixing mussel-caused damages to cooling water systems, critical parts of the CAP's 336-mile canal that moves water from Lake Havasu to Phoenix and Tucson. 5/12/2021 Influx of new boats could spread destructive quagga mussels https://www.azcentral.com/story/news/local/arizona-environment/2020/09/07/influx-new-boats-could-spread-destructive-quagga-mussels/5688432002/ 5/5 “Once the quaggas lay down, they start trapping all the other stuff in there as well,” said Scott Bryan, a senior biologist at CAP. “It becomes a matrix of organic muck in those coolers.” Over the course of a year, CAP piloted a potential fix by drip-releasing a copper-based molluscicide in its water system at Lake Havasu. Bryan said the solution kept mussels from attaching to piping and was considered a success. It’s now being implemented in all six of the CAP's water systems with the goal of having each drip-system fully operational by mid-2021. According to Bryan, there’s been no trace of copper downstream of the pumping plant. “The upfront capital cost of building these systems is going to be one of our biggest expenses. So will the ongoing cost of buying and injecting product into the system,” Bryan said. “But in the long-term that’s just a fraction of what we would have spent on constant maintenance.” Bryan did not share the exact cost of construction but said there should be no increase in customer rates because expenses would come out of operating budget. The 2020-21 Biennial Budget shows CAP spent over $255 million in operating expenses this year. “As government agencies, lake managers and utility companies, we can’t be at every spot where people are recreating.” McPherson said. “It’s up to the citizens to understand how important this issue is and act accordingly.”