Topic: Invasive species

Oxygen levels in the world’s temperate freshwater lakes are declining rapidly — faster than in the oceans — a trend driven largely by climate change that threatens freshwater biodiversity and drinking water quality. Research published today in Nature found that oxygen levels in surveyed lakes across the temperate zone have declined 5.5% at the surface and 18.6% in deep waters since 1980. 

In terms of sheer size, Nordic Aquafarms’ land-based aquaculture facility, slated for construction on the Samoa Peninsula, would be the largest development project Humboldt County has seen for decades, maybe since the heyday of the timber industry. The facility’s five buildings — including two massive production modules where Atlantic salmon would be raised inside fully-contained recirculating tanks — would total 766,530 square feet, nearly an acre larger than the footprint of the Bayshore Mall. It’s been more than two years since the Norwegian company announced its ambitious plans, and the environmental review period was scheduled to wrap up this week. 

Seven years ago, after the fish died, Sarah Ryan decided she couldn’t wait any longer for help. California at the time was in the depths of its worst drought in the last millennium and its ecosystems were gasping. For Ryan, the fish kill in Clear Lake, the state’s second largest and the centerpiece of Lake County, was the last straw. Ryan is the environmental director for Big Valley Rancheria, a territory of the Big Valley Band of Pomo Indians that sits on the ancient lake’s western shore. She and others raised alarms for several years about increasingly dire blooms of toxic cyanobacteria. 

Related article: 

• High Country News: The toxic, soupy biomass choking water systems in California 

As we rapidly enter another drought, long-standing questions on ecological impacts of increased temperatures, reduced water levels and flows re-emerge. This reality recently reminded me of some of my own previous work looking at growth rate variations of largemouth bass in response to droughts in the southeastern USA (Rypel et al. 2009). Results from this work may be useful/interesting for biologists and managers in California considering similar questions.

Lake Tahoe is known for its mesmerizing clear, blue water. But there are multiple threats to the lake that may someday change the color and worse, downgrade the quality of the water. Some of the most difficult of these threats to address are invasive species, specifically two types of aquatic plants that are not native and are moving from an area of the lake known as the Tahoe Keys into Lake Tahoe itself. The plants are Eurasian watermilfoil and curly-leaf pondweed. 

It’s nothing less than an invasion. Interlopers are coming into California by land, by sea…and by FedEx. That’s what happened with the European green crab, a voracious cannibal that stowed away in packages of worms sent by overnight delivery to commercial fisherman in California. Unknown to anyone, the tiny crustaceans were concealed in seaweed that wrapped the cargo and were freed into the Pacific when fishermen tossed it overboard. … California spends $3 million a year attempting to eradicate nutria, a large, homely, orange-toothed rodent that destroys wetlands and bores holes into levees. Another $3 million a year goes to educating boaters about quagga mussels, which hitch rides on hulls and cling to equipment in the state’s vast water transport system.  And, for the last 20 years, authorities have spent more than $34 million to manage Atlantic cordgrass in the San Francisco Bay-Delta.

The Delta Stewardship Council (Council) announced the hiring of Ryan Stanbra, the Council’s legislative and policy advisor, to the key post of chief deputy executive officer. … Appointed by Governor Brown in 2015, Ryan joined the Council in the role of legislative and policy advisor. He has played a pivotal role in advising on critical Council initiatives like implementation of reduced reliance on the Delta, interagency coordination and outreach for the Delta Levees Investment Strategy, increasing funding for critical science investments, and more. He has served in the acting chief deputy executive officer role since January.

The Division of Boating and Waterways (DBW) will be accepting grant applications for quagga and zebra mussel infestation prevention programs from March 22 through April 30, 2021. All applications must be received by 5 p.m. on Friday, April 30, 2021. … California water body authorities have recognized the westward spread of mussel infestation via the Colorado River System and the potential harm to state waterways should lakes and reservoirs become invaded. To help prevent California waterways from infestation, DBW provides grants to entities that own or manage any aspect of water in a reservoir that is open for public recreation and is mussel-free.

Some invasive species targeted for total eradication bounce back with a vengeance, especially in aquatic systems, finds a study led by the University of California, Davis. The study, published in the journal PNAS, chronicles the effort — and failure — to eradicate invasive European green crabs from a California estuary. The crabs increased 30-fold after about 90 percent had been removed. The study is the first experimental demonstration in a coastal ecosystem of a dramatic population increase in response to full eradication. … For the PNAS study, researchers in 2009 began intensive efforts to eradicate the European green crab from Stinson Beach’s Seadrift Lagoon. 

Zebra mussels — fingernail-sized mollusks named for their striped shells — are benign in their native Black Sea and Caspian Sea ecosystems. But they are disastrous almost everywhere else. Since they were first discovered in the Great Lakes in 1986, these rapid-spawning animals have infested every watershed in the Lower 48 except the Columbia River Basin….The mussel found in [a pet store in] Seattle came from the California distributor….

California’s rivers, wetlands, and other freshwater ecosystems are in poor health. Water management practices, pollution, habitat change, invasive species, and a changing climate have all taken a toll, leaving many native species in dire straits. And the current approach for managing freshwater ecosystems is not working. In this video Jeff Mount, senior fellow at the PPIC Water Policy Center, discusses the many benefits these ecosystems bring to California, and outlines a path for improving their condition to secure these benefits for future generations.

[S]cientists were having a hard time telling delta smelt apart from a fish species from Japan called wakasagi. … Wakasagi were introduced by the government in the 1950s. There’s no shortage of them here or in Japan. Especially when they’re young, to the naked eye they look virtually identical to deltas. They’re so similar, in fact, to the nearly extinct fish that scientists were worried about hybridization — that this plentiful species and the delta smelt would start hooking up, making mixed-species fish babies.

Conservation groups said 80 species were known to have gone extinct, 16 in the last year alone. Millions of people rely on freshwater fish for food and as a source of income through angling and the pet trade. But numbers have plummeted due to pressures including pollution, unsustainable fishing, and the damming and draining of rivers and wetlands. The report said populations of migratory fish have fallen by three-quarters in the last 50 years. Over the same time period, populations of larger species, known as “megafish”, have crashed by 94%.

For the better part of the last two centuries, the Sacramento-San Joaquin Delta has been modified in any number of ways to meet the demands of Californians. But a new wide-ranging study looks at what might be the most serious Delta threat that doesn’t come in the form of an excavator – global warming. 

BlueGreen Water Technologies has secured approval from the California Department of Pesticide Regulation for its algaecide, Lake Guard Oxy, for commercial application in the US state. According to the firm, in the past year, there has been a marked rise in the severity of toxic algal blooms, also called as ‘blue green algae’ and ‘red tide’ in several of the state’s lakes as well as on the coasts.

The Kings River Conservation District, along with co-applicant Tulare Lake RCD, received this grant to help remove invasive species and debris from levees and riverbank along the Kings River, improve water flow, strengthen flood protection, increase carbon capture, and improve delivery of clean water to downstream users.

The Trump administration Wednesday announced a newly strengthened team effort to combat invasive mussels.

President Trump’s signature on a bill expanding the fight against a large, vexatious rodent called the nutria is an instructive victory for a newly reelected Democrat from a swing district in California’s San Joaquin Valley.

The pesky 3-foot-long, buck-toothed nutria is getting the better of California. The large rodent is chewing up rivers and wetlands and threatening to mow down farmland and infrastructure, and the state is struggling to contain it.  Relief may be on the way.

It’s been a busy spring and summer for trapping nutria in Merced and Stanislaus counties. State Fish and Wildlife have caught nearly 1,000 nutrias along the San Joaquin River corridor and in the grasslands.

Volunteer citizen scientists working with the League to Save Lake Tahoe conducted surveys of Donner and Spooner lakes to detect aquatic invasive species, and restored native wetland habitat in Johnson Meadow in September. Both efforts are aimed at preserving the Tahoe-Truckee region’s unique ecology.

The collaborative design process for the Franks Tract Futures project brought initially skeptical local stakeholders on board and is being hailed as a model for future initiatives. Yet major uncertainties remain as interested parties explore the challenges of implementing a complex redesign of a big chunk of the Delta.

Groups in the Tahoe Basin are using new technology to fight invasive species and decreasing lake clarity. Researchers at University of Nevada, Reno and Tahoe Regional Planning Agency have been testing a UV light equipped vessel to control aquatic invasive plants in the Tahoe Keys.

The Franks Tract Futures Project is asking for additional comments on the State’s revised concept design.1 The project is an outgrowth of the State’s 2016 Delta Smelt Resilience Strategy, which recognized that Franks Tract is a death trap for state and federally listed Delta smelt.

The San Francisco Estuary is a dynamic and altered estuary that supports a high diversity of fishes, both native and non-native. … Since the 1950s, various agencies and UC Davis have established long-term surveys to track the status of fish populations. These surveys help scientists understand how fishes are responding to natural- and human-caused changes to the Estuary.

The new tool is a light fixture called an array mounted under a working barge, which trolls the marina dousing the plants on the bottom with UV-C light, a short-wave electromagnetic radiation light that damages the DNA and cellular structure of aquatic plants.

Related article:

• University of Nevada, Reno: Blog: Vessel equipped with ultraviolet light attacks invasive aquatic plants at Tahoe

Signal crayfish are displacing Shasta crayfish. Believed to have already forced the sooty crayfish (Pacifastacus nigrescens) to extinction, signal crayfish have outcompeted their Shasta cousins to near extinction. However, a growing trend of environmental monitoring, typically referred to as eDNA, is helping scientists isolate the scarce species in an effort to save it.

Senator Dianne Feinstein (D-Calif.) joined Senator John Kennedy (R-La.) to introduce legislation to amend the Nutria Eradication and Control Act. The legislation would authorize an additional $6 million a year to increase assistance for states that implement initiatives to eradicate the invasive species.

In 2003, Congress passed The Nutria Eradication and Control Act, which established a fund to help Maryland and Louisiana battle the animals. Recently, the House of Representatives passed bipartisan legislation that now allows California to also receive support. The bill now heads to the Senate.

Looking at the water hyacinth’s lovely lavender flowers and lush green leaves, it’s easy to see why it was brought here from South America. But too much of a good thing can cause trouble, and few things turn into “too much” as quickly as water hyacinths (Eichhornia crassipes).

Crawdads, crayfish, craydids: whatever you choose to call those crustaceans that bear a resemblance to mini-lobsters, they are probably not native to our creeks and waters.

We want to know if removing carp can improve water quality and reduce harmful algal blooms, HABs. Carp are widely known to bioturbate sediments where previously deposited nutrients like phosphorus are bound. Re-suspension of phosphorus by carp leads to HABs, creating an interesting link between fish and human health.

Roland Knapp, research biologist at the University of California Sierra Nevada Aquatic Laboratory, explained that a fish-less habitat along with increased resistance to chytrid fungus can allow populations to rebound and increase. Knapp’s research findings have shown the frogs being able to adapt to the disease over time. … “I have a lot of hope. I wouldn’t have said that 10 years ago.”

Billions of invasive Mysis shrimp, introduced in the 1960s as a food source for native trout, live in Lake Tahoe, where they have almost eaten to extinction the native zooplankton that historically helped keep the lake blue and clear.

Discovery Bay residents are growing irritated with invasive aquatic plants and the COVID-19 pandemic slowing down weed abatement. While the town can be the ideal place to enjoy a vacation lifestyle year-round, this spring’s crop of weeds is ruining the bays and inhibiting movement around docks on the west side of town.

California State Parks’ Division of Boating and Waterways on Thursday announced plans to control aquatic invasive species in the Sacramento-San Joaquin Delta. Beginning April 20, the DBW will start herbicide treatments on floating aquatic vegetation such as water hyacinth and alligatorweed, and submersed aquatic vegetation such as Egeria densa and curlyleaf pondweed.

It is well known that warm water fish (bass and bluegill) have diminished wild trout populations at Lake Tahoe. … However, getting rid of the illegally planted warm water fish isn’t altogether realistic, and the real agenda is only hinted at: Protection for recently planted Cutthroat trout, declared as the only ‘worthy’ fish allowed in the lake.

The decision ends a 1996 policy that committed the state to sustaining a population of about 1 million striped bass in the Delta and other California waterways. They’re voracious, nonnative predators that can weigh as much as 60 pounds. They’re especially popular among anglers. It’s unclear exactly how many striped bass are in the state, but the number is believed to be fewer than 300,000.

The state program that works to control the invasive aquatic plant hydrilla is planning a meeting in Lake County next week to take input on its eradication project.

Hydrilla (Hydrilla verticillata) is a highly invasive aquatic plant that has the capacity, by forming dense mats that restrict dissolved oxygen levels, to disrupt many of the water-based activities that are synonymous with Lake County.

These changes will be substantial, multi-faceted, and often rapid. Some changes will be irreversible. Many changes are inevitable. Some will say today’s Delta is doomed. It will be important for California to develop a scientific program that can help guide difficult policy and management discussions and decision-making through these challenges.

Dr. Rachel Johnson is a research biologist with the NOAA’s National Marine Fisheries Service and UC Davis with over 15 years’ experience working on various aspects of conservation and fisheries biology. In this presentation from the 2019 State of the Estuary conference, Dr. Johnson discussed the importance of developing a holistic framework among aquatic ecosystems and management authorities.

Through financial support from various grant funding, CDFA is implementing a five-phase process for nutria eradication that consists of survey, knockdown, mop-up, verification, and surveillance. CDFW staff have been working the landscape by dividing areas into 40-acre grids to ensure that nothing is overlooked.

Community members, supported by staff from the League to Save Lake Tahoe, Tahoe Resource Conservation District and California State Parks, have wrapped up a three-year effort to survey the Upper Truckee River for aquatic invasive plants.

Invasive fish species have long been a challenge for scientists in the Grand Canyon because they attract fishermen but can devour threatened native species. Now, the National Park Service is ready to try a new approach to keeping things in balance: pay fishermen and women to harvest one of the worst offenders, the brown trout.

Just how far will Gov. Gavin Newsom go in his high-profile fight with the Trump administration over environmental protections? The next few months will provide an answer, as Newsom is forced to take a stand on Trump rollbacks in a long-contested battleground — the Northern California Delta that helps supply more than half the state’s population with drinking water and fills irrigation canals on millions of acres of farmland.

A rookie California lawmaker plans to haul a 20-pound rodent carcass into Congress on Tuesday to press his colleagues for money to fight an invasive species wreaking havoc on his district. Rep. Josh Harder, D-Turlock, hopes a hearing on his bill will convince his colleagues that funding to stop invasive nutria in California’s Central Valley is sorely needed …

There’s no certain answer as to how the nutria population re-emerged after being declared eradicated in California decades ago but the population is spreading and causing serious concern. The Department of Fish and Wildlife was recently awarded $10 million to wipe out the large, invasive rodents and that effort is now well underway.

UC Davis researchers have seized on a new explanation for the continued dinginess of Lake Tahoe’s blue waters — tiny invasive shrimp. … To make Tahoe shrimp-free, the researchers are proposing to remove the crustaceans with trawlers and to mass market Omega-3 fatty acids extracted from the catch.

Nutria, a giant invasive rodent originally from South America, might be the size of a beagle, but unlike a beagle you can’t keep them in your home. The California Fish and Game Commission is looking to correct a gap in the law that restricts what pets may lawfully be owned by including nutria among the list.

Rep. Josh Harder has focused much of his first year in office on local issues such as water storage and the effects of almond tariffs on Central Valley farmers. Now he is training his attention on the nutria, a semi-aquatic rodent that has drawn the ire of environmentalists, farmers and local officials alike.

Massive invasive rodents are chewing up wetlands in Merced and other counties. Area leaders say the problem needs more money to eradicate the animals, before they are out of control.

The initial objectives of the restoration project were to: improve habitat for the Delta smelt, reduce saltwater intrusion, reduce submerged aquatic weeds and reduce invasive non-native fish species that feed on native fish. Carl Wilcox, a CDFW policy advisor explained the objectives are now more broad and include accommodations for recreational and economic activities that are key to the region’s residents.

The rapid proliferation of the quagga mussel has major implications for power plant reliability. The U.S. Bureau of Reclamation installed a groundbreaking solution at Parker Dam in Arizona that virtually eliminated the invasive species from hydropower cooling systems.

Besides choking out much-loved natives such as the golden poppy, which is the state flower, Ward’s weed is a wildfire hazard. Each year it dies off and turns into a brown mass of thin, dry brush, like a tiny tumbleweed, that can go up in flames with a spark.

An invasive bamboo-like species called arundo is encumbering the natural ecology of the Salinas River and increasing flood risk to nearby farmland. But the conservation agency charged with protecting the area recently secured nearly $3 million from state coffers for the purpose of fighting the invasion.

Conservationists and weekend volunteers have toiled in the Bolsa Chica Wetlands for years, weeding out invasive plants and replanting native vegetation squeezed out by the invaders. … Now, these wildlife custodians are expanding their botanical battle across Pacific Coast Highway to the sand dunes of Bolsa Chica State Beach. After all, no matter how many enemy plants are removed from the wetlands, ocean winds will carry more seeds from  non-native plants growing in the dunes.

On our Bay-Delta Tour June 5-7, participants will hear from a diverse group of experts including water managers, environmentalists, farmers, engineers and scientists who will offer various perspectives on a proposed tunnel project that would carry water beneath the Delta, efforts to revitalize the Delta and risks that threaten its delicate ecological balance.

More than 400 nutria have been captured in the first year of an effort to eradicate the invasive South American rodent from California. The state Department of Fish and Wildlife said Monday the semi-aquatic rodents were trapped in five counties in the San Joaquin Valley. Nutria are an agricultural pest, destroy wetlands critical to native wildlife and threaten water delivery and flood control infrastructure through destructive burrowing.

Related article:

• News release: CDFW Marks One-Year Anniversary of Nutria Eradication Effort: Biologists Report More Than 400 Invasive Rodents Captured to Date
• Daily Democrat: Flyway Nights explores Nutria invasion of California

In California, [Jerry] Schubel saw an opportunity to turn the energy, food and water issues facing the state into a sustainable model showing how people can live in harmony with the Earth and the ocean, and thrive. That model required deep collaboration, a commitment to educational resources for the public and an aquarium willing to take a risk.

The state Department of Fish and Wildlife has been battling the destructive Nutria for two years. State biologists believe it will be another three years before they win the war against the pesky rodent. The nutria is considered a triple threat to Valley wetlands, agriculture and water delivery systems.

What better way to decompress from a stressful federal government job than by trekking 2,600 miles on foot from Mexico to Canada? That’s what Jared Blumenfeld, the new head of the California Environmental Protection Agency, did three years ago, setting out on the arduous and beloved Pacific Crest Trail that traces California’s searing deserts, rugged mountains and sparkling coastline.

The California Department of Food and Agriculture, working in cooperation with the Shasta County Agricultural Commissioner’s Office, has eradicated two hydrilla infestations within the cities of Redding and Anderson, ending a quarantine that began on July 18, 1996. Hydrilla, an invasive aquatic weed, was last detected in Shasta County in 2006.

Metropolitan General Manager Jeffrey Kightlinger said … the agency intends to work constructively with the Newsom administration on developing a WaterFix project “that addresses the needs of cities, farms and the environment.” But Kightlinger expressed frustration that the project will be delayed even more.

Related articles:

• Santa Clarita Valley Signal: Water GM holds hope that tunnel still on track

At long last, the Sacramento-San Joaquin River Delta twin-tunnels boondoggle is dead. Good riddance. Gov. Gavin Newsom made that official Tuesday during his State of the State address, calling instead for a smaller, single-tunnel approach that would include a broad range of projects designed to increase the state’s water supply. Bravo. It’s a refreshing shift from Gov. Jerry Brown’s stubborn insistence that California spend $19 billion on a project that wouldn’t add a drop of new water to the state supply. 

The Humboldt Bay Harbor, Recreation and Conservation District today approved the lease agreement, which will last 30 years after an initial 3-year period set aside for vetting and permitting the company. … But some fishermen and other county residents voiced skepticism about how closely the company has been vetted, as well as criticism of the district’s swift decision to sign onto the lease.

Despite many high priority issues on his plate, one of Gov. Gavin Newsom’s first tests will be how he deals with California’s water challenges and opportunities. Unfortunately, in the last days of his term Gov. Jerry Brown made a bad bargain with the Trump administration and special interests. It’s yet another mess for the new governor to mop up.

While campaigning for president in 2016, Donald Trump promised a cheering Fresno crowd he would be “opening up the water” for Central Valley farmers… Trump took one of the most aggressive steps to date to fulfill that promise Tuesday by proposing to relax environmental regulations governing how water is shared between fish and human uses throughout the Central Valley. 

Related articles:

• Maven’s Notebook: News release: Reclamation releases biological assessment for California water operations
  

The nutria invasion of California continues. Greg Gerstenberg, a biologist and nutria operations chief with the California Department of Fish and Wildlife, said 372 nutria had been trapped in the state as of Jan. 10. Bruce Blodgett, executive director of the San Joaquin Farm Bureau Federation, wants farmers and others who maintain levees to be aware.

The Santa Clara Valley Water District made a grave miscalculation in suing the State Water Board over the Bay Delta Water Quality Control Plan. By alienating the remnants of the environmental community who have supported them in recent years, they are jeopardizing future projects and funding measures that will require voter approval.

A Dallas-based engineering firm is being tapped to help design California’s plan to bolster its water supply system. Jacobs’ initial $93 million contract is for preliminary and final engineering design of a 15-year program known as California WaterFix. The Golden State’s largest water conveyance project carries a $17 billion pricetag. WaterFix, slated to begin this year, will upgrade 50-year-old infrastructure dependent on levees, which the state said puts clean water supplies at risk from earthquakes and sea-level rise.

Bureau of Reclamation Commissioner Brenda Burman today named Ernest A. Conant director of the Mid-Pacific Region. Conant has nearly 40 years of water law experience and previously served as senior partner of Young Wooldridge, LLP.

Citing what they say would be a disastrous decision for the region, the Oakdale and South San Joaquin Irrigation Districts have joined with other members of the San Joaquin Tributaries Authority (SJTA) in a lawsuit challenging the state’s right to arbitrarily increase flows in the Stanislaus and two other rivers.

The confluence of California’s two great rivers, the Sacramento and the San Joaquin, creates the largest estuary on the West Coast of the Americas. Those of us who live here call it, simply, the Delta.  It is part of my very fiber, and it is essential to California’s future. That’s why we must save it.

In an attempt to block the state’s plan to divert more water toward the Sacramento-San Joaquin River Delta and away from the Bay Area, the Santa Clara Valley Water District has filed a lawsuit arguing the project could significantly reduce the local water supply. If the plan advances, the water district might have to spend millions of dollars to obtain alternate water supplies and pull up more groundwater.

The State Water Resources Control Board proved back on Dec. 12 that it wasn’t listening to a single thing anyone from our region was saying. By voting to impose draconian and scientifically unjustifiable water restrictions on our region, four of the five board members tuned out dozens of scientists, water professionals and people who live near the rivers.

Jon Rosenfield: Last month the State Water Resources Control Board finally required increased flows from three San Joaquin River tributaries, as the first step in a process to update water quality standards for the San Francisco Bay estuary. The board opted for weaker environmental protections in order to reduce impacts to agribusiness and San Francisco, ignoring the potential for changed agricultural practices and investment in sustainable water use to ease or eliminate the impact of reduced water diversions.

In 2014, plant biologists with the California Department of Agriculture reported an alarming discovery: native wildflowers and herbs, grown in nurseries and then planted in ecological restoration sites around California, were infected with Phytophthora tentaculata, a deadly exotic plant pathogen that causes root and stem rot. While ecologists have long been wary of exotic plant pathogens borne on imported ornamental plants, this was the first time in California that these microorganisms had been found in native plants used in restoration efforts.

The report issued by California’s State Water Resources Control Board marks a key step in a decade-long effort to remove four hydroelectric dams and restore the health of the Klamath River. The dam-removal project is part of a broader effort by California, Oregon, federal agencies, Klamath Basin tribes, water users and conservation organizations to revitalize the basin, advance recovery of fisheries, uphold trust responsibilities to the tribes, and sustain the region’s farming and ranching heritage.

The U.S. Senate approved a compromise policy Wednesday on dumping ship ballast water in coastal ports and the Great Lakes, a practice blamed for spreading invasive species that damage the environment and the economy. The plan, part of a $10.6 billion Coast Guard budget authorization bill, includes provisions sought by environmentalists as well as the cargo shipping industry.

The California Department of Fish and Wildlife hit a milestone in its ongoing efforts to control the state’s nutria infestation on Friday morning when they successfully trapped Nutria number 300 at a pond in Merced County. … The department is currently expanding its operations in San Joaquin County, and is concerned by several reports of nutria on the doorstep of the Sacramento–San Joaquin River Delta, a critical region for California’s agricultural infrastructure.

For years, state boats have sprayed thousands of pounds of herbicides into the Sacramento-San Joaquin Delta to kill invasive aquatic weeds. And, for years, California officials have insisted they closely monitor their chemical use to protect the ecologically fragile estuary and the drinking and irrigation water the Delta supplies to millions of Californians. A pending court case casts fresh doubt on those claims.

Blindly feeling along a section of fabric mat underneath the water’s surface at Lakeside Marina, a diver grabs a U-shaped piece of rebar and begins hammering away. At only a handful of feet below the water’s surface visibility drops to zero, making work difficult, but it’s an essential job in what could be a vital piece in the puzzle to solve Lake Tahoe’s aquatic invasive species problem.

The call came from a wildlife trapper working in the wetlands of central California. “I think I caught a nutria,” the man said. Greg Gerstenberg, a state biologist, was thrown. “I was like, ‘a what?’”

An 8-year-old chocolate Labrador named Popeye is patrolling Lake Nacimiento this weekend, using his sensitive sniffer to protect the reservoir from a dangerous invader. He and his friends — Nemo, Captain, Noah and Sinbad — are the Mussel Dogs, a group of Labs, a mutt and a German Shepard specially trained to inspect boats for invasive species and protect California’s waterways from quagga and zebra mussels.

An invading army of moths is stripping the leaves from aspen trees around Lake Tahoe, and state officials are seeking the public’s help to document the problem. White satin moths are a non-native defoliator of aspens, cottonwoods, willows and other trees.

DNA analysis confirmed this week that stowaway shellfish intercepted at the Lake Mendocino boat ramp early this month were invasive quagga mussels, as initially feared. The finding by state Fish and Wildlife personnel validates just how close the region came to confronting a destructive scourge.

A specially trained dog named Noah is receiving well-deserved praise after preventing a mussel-infested watercraft from launching Saturday in Lake Mendocino — a frighteningly close call that public officials say underscores the need for long-delayed, full-time measures to protect regional reservoirs and critical infrastructure from exposure to the destructive organisms.

For more than 100 years, invasive species have made the Sacramento-San Joaquin Delta their home, disrupting the ecosystem and costing millions of dollars annually in remediation. … Even though invasive plants and animals long have been known to exist in California’ water hub, tracking their extent in an area as large as the Delta — 738,000 acres — is an uneven task that could benefit from greater coordination and funding, a panel of experts recently told the Delta Independent Science Board.

The organism, responsible for the catastrophic decline of the Sierra Nevada yellow-legged frog and 200 other species, emerged from East Asia in the early 1900s and is spreading by the pet trade and the expansion of global trade, according to an international research consortium of 38 different institutions.

Scientists think they’ve found the reason why amphibian populations across the Western United States are in decline. The culprit: imported American bullfrogs used for food and as pets.