Invasive species, also known as exotics, are plants, animals,
insects, and aquatic species introduced into non-native habitats.
Without natural predators or threats, these introduced species
then multiply.
Often,invasive species travel to non-native areas by ship,
either in ballast water released into harbors or attached to the
sides of boats. From there, introduced species can then spread
and significantly alter ecosystems and the natural food chain as
they go. Another example of non-native species introduction
is the dumping of aquarium fish into waterways.
Invasive species also put water conveyance systems at risk. Water
pumps and other infrastructure can potentially shut down due to
large numbers of invasive species.
An invasion of smallmouth bass from the Great Lakes region is
spreading to new areas of the Colorado River in Arizona. The
bass have already thwarted efforts to save threatened native
fish in the upper river basin, and wildlife officials are
fighting to keep the same from happening below Lake Powell,
even if it requires cranes, excavators and maybe one day, a
giant metal curtain. Federal officials say they took a major
step in fighting the bass invasion below the Glen Canyon Dam in
June. The National Park Service and Bureau of Reclamation have
cleared out a warm backwater in the river where bass and other
invasive species used to spawn, eliminating a critical resource
for the predatory fish that could wipe out one of the last
holdouts for some of the Colorado River’s threatened and
endangered fish. Every bass that spawned in the slough
became a threat to native fish, experts say. Smallmouth bass
eat native fish eggs and young.
The first discovery of golden mussels in North
America at Rough and Ready Island near Stockton in San Joaquin
County has water managers throughout California on the alert,
including the Yuba Water Agency, which manages New Bullards Bar
Reservoir. On Tuesday, the Yuba Water Agency announced that it
will launch a new watercraft screening pilot program later this
summer at New Bullards Bar Reservoir in Yuba County. The pilot
program aims to prevent the spread of the golden mussel, a
highly invasive species found in the Sacramento-San
Joaquin Delta last fall that could pose a
significant ecological and economic threat to the Yuba River
watershed. … Thus far, all the sightings of golden
mussel have been concentrated in the delta, although five
additional sightings have been reported in the San Joaquin
Valley.
Before enjoying Ruth Lake this summer, be sure to clean, drain
and dry all gear, boats and trailers to prevent the spread of
the invasive golden mussel. The golden mussel, native to East
and Southeast Asia, was first documented in California in 2024.
Like quagga and zebra mussels, the golden mussel is capable of
rapidly spreading, wreaking ecological health and threatening
water infrastructure and water quality. Thomas Jabusch of the
California Department of Fish and Wildlife and Michiko Mares of
the Humboldt Bay Municipal Water District join the program to
golden mussels, their threat, and what you can do to stop the
spread of this invasive species.
Golden mussels are an invasive aquatic species that disrupt
ecosystems, filter away nutrients and damage shorelines
– and they were recently spotted on a boat trying to enter
Lake Tahoe. … This season, boating in California’s
Folsom Lake State Recreation Area requires a mandatory 30-day
quarantine or decontamination, while other water bodies like
Shasta Lake do not require any pre-launch inspection. No matter
the protocol, the spread of the golden mussel has raised alarm
among scientists and advocates, and its spotting in the Tahoe
basin is no small scare. … In the past, some
marinas shut down completely after the discovery of a new
invasive species – this happened in Lake Mead after the 2007
introduction of zebra mussels. Because Tahoe is so intertwined
with outdoor recreation, though, enhanced enforcements need to
be thoughtfully crafted.
… In new research published in the journal Biological
Conservation, (UC Davis PhD candidate Sidney) Woodruff and her
colleagues propose a possible — though intensive —
countermeasure: a near-total eradication of the bullfrog from
habitats that it has invaded. The result was the striking
recovery of the Northwestern pond turtle, California’s only
native freshwater pond turtle species, at a couple of remote
bodies of water within Yosemite National Park.
… Woodruff and her colleagues conducted a combination of
night surveys to remove the adults and day surveys to go after
bullfrog egg masses. Across two sites, she estimates they
removed some 16,000 bullfrogs, amounting to a near-complete
eradication. And after several years of removal, “we came
across our first couple of small pond turtle hatchlings and
juveniles swimming out in the environment,” says Woodruff.
An invasive species of mussels first discovered in the Port of
Stockton is now getting attention in Washington, D.C. Rep. Josh
Harder, D-Tracy, said this week he has joined other Delta-area
members of Congress in introducing a bill aimed at trying to
halt the spread of golden mussels. The mollusks have been found
in various parts of the Delta and as far south as Bakersfield.
The discoveries have prompted a variety of measures, including
closure of at least one popular San Joaquin County reservoir to
the launching of boats, kayaks and other watercraft. Perhaps
most alarming, officials at Lake Tahoe say their inspectors
found a boat that the owner had hoped to launch that was
encrusted with golden mussels. … Harder said the
bill that was introduced will protect Delta and
waterways by initiating a rapid response program to
contain and eradicate infestations. It also will fund new
technology and inspection stations and foster coordination
between local, state and federal agencies.
Last weekend, watercraft inspectors found golden mussels,
a highly invasive aquatic species, on a 65-foot boat
that was headed to Lake Tahoe. Experts say golden
mussels pose an extreme threat to Lake Tahoe. To stop
the mussels from getting into the lake, this spring, Tahoe
implemented much stricter measures that go beyond the norm,
requiring that every single motorized boat not just be
inspected but also be decontaminated before hitting the
water. The boat carrying the golden mussels was put into
quarantine until it’s deemed risk-free, according to the Tahoe
Environmental Planning Agency. The close call was the first
time officials intercepted the golden mussels at one of Tahoe’s
boat inspection stations. … If the mussels were to reach
Lake Tahoe, they would wreak havoc on the ecosystem and degrade
water quality, and there’s no getting them out, experts
say.
More than 90% of popular freshwater fish in Southern California
are carrying human-infecting parasites, researchers say. This
poses a significant danger for those who like to eat freshly
caught freshwater fish. But there are ways to protect yourself.
The parasites are called trematodes. Two species of the
flatworms were discovered in California’s freshwater fish,
according to a study published Tuesday in the Journal of
Infectious Diseases. The tiny, flattened and sluglike creatures
can cause gastrointestinal problems, weight loss and lethargy
when a person eats an infected fish. In some rare and
severe cases, the parasites have caused strokes or heart
attacks. … In fact, even when a person has fallen ill
from a locally caught infected freshwater fish, their
healthcare provider will typically ask if the patient has
recently traveled outside of the United States, Hechinger said.
Lake Tahoe watercraft inspectors on Friday identified highly
invasive golden mussels on a vessel at the Alpine Meadows,
Calif. inspection station. This is the first interception of
the new invasive species by Lake Tahoe watercraft inspectors
since their first detection in North America in the
Sacramento-San Joaquin River Delta in October, 2024.
… Inspectors at the Alpine Meadows station conducted an
initial decontamination of the 65-foot vessel. It will be held
under quarantine under California Department of Fish and
Wildlife regulations until the vessel is deemed risk-free.
Watercraft Inspection Program managers are also coordinating
with Nevada Division of Wildlife and other state agencies and
continue to share information on all detections with agencies
in both states and the western U.S. As new threats to Lake
Tahoe emerge, the emphasis on following Clean, Drain, Dry
protocols remains for all boaters, paddlers, anglers, and
beachgoers.
Spending warm summer days at the lake might look a little
different for some people this year. Lake Camanche has been
added the long list of Northern California waterways,
restricting boats and other watercraft because of invasive
golden mussels. … Objects like
paddleboards or kayaks are not allowed because of the recent
spread of the golden mussel, discovered for the first time in
Northern California last year. According to the East Bay
Municipal Utility District, unless you have a boat with a
permanent slip at Camanche, or were in the water or in on site
dry storage when boat launches closed last November, your
watercraft is banned. … Tiwana Cypress and her husband
have been camping at Lake Camanche for 10 years.
… Cypress said she’s seen other options, like taking
advantage of the lake’s boat rentals.
When the weather heats up, many want to grab a drink, get on a
boat and spend time with friends and family on the water. This
year, at Lake Camanche, it’s a different story. “We’ve taken
the precaution, a difficult one, to shut down our boat launches
for this year as we try to get our arms around this and figure
out the best way to prevent its introduction to East Bay MUD’s
water system,” East Bay Municipal Utility District spokesperson
Christopher Tritto said. The reason is because of the recently
discovered golden mussel found in the
Sacramento and San Joaquin Delta. While this invasive species
hasn’t made it into the reservoir, the utility district is
taking this ban a step further: no kayaks, no paddleboards, and
more. The only boats allowed are those with a permanent
slip or boats that have been in the water before the launches
closed.
There is now another option for boaters hoping to get out on
Folsom Lake amid golden mussel restrictions.
Boats can now undergo a hot water decontamination — skipping
the 30-day quarantine that was previously the only
option. The rules are aimed at preventing an infestation
of golden mussels, which were recently identified in the
Sacramento-San Joaquin Delta and that “pose a significant
threat to the ecological health of all waters of the state, its
water conveyance systems, infrastructure, and water quality,”
California State Parks said. California State Parks lists
one location that is authorized to conduct decontaminations and
place a green seal on vessels headed for Folsom Lake – Mello
Marine. … It’s a service that requires a lot of water
and Mello’s setup was designed with that in mind – using pond
liners, trenches, filters and holding tanks.
A boat going through the inspection process at the Thermalito
Forebay (at Lake Oroville) on Wednesday was
deemed positive for the golden mussel, an invasive species that
the California Department of Water Resources is trying to keep
away from local waterways. Inspections began on Monday at the
Forebay where boaters must go through a checkpoint where
workers thoroughly check the watercraft for standing water and
signs of the mussel. DWR issued a statement on Thursday that
said the mussel was found on a pontoon boat. According to the
statement, the boat was purchased on Wednesday morning by
residents of the Oroville area. The statement said the
watercraft had been away from the waters in the delta for “an
unknown period.” “Staff immediately contacted the California
Department of Fish and Wildlife for further inspection and
decontamination,” the release from DWR said.
The call of American bullfrogs was deafening when scientists
from the University of California, Davis, first began
researching the impact of invasive bullfrogs on native
northwestern pond turtles at Yosemite National Park. … But
the ponds of Yosemite sound different today, with a chorus of
native species making themselves heard. The researchers’ study,
published in the May issue of the journal Biological
Conservation, found that as the park was depopulated of
bullfrogs, northwestern pond turtles began to return. The study
suggests that removing invasive bullfrogs may be necessary in
priority conservation areas to help pond turtle populations
recover.
The western U.S. is experiencing a late-season snow drought,
according to an update Wednesday by the National Oceanic and
Atmospheric Administration’s National Integrated Drought
Information System. The diminished snowpack could result in
water supply issues and increased wildfire risk in the coming
months, the authors wrote. Above-normal temperatures and a lack
of precipitation in April and early May caused depletions even
in basins where snow had piled up in prior months.
… “While the rate of the snowmelt has not had a major
impact on forecasted April through July seasonal runoff, below
average spring precipitation has lowered runoff projections
slightly,” said Andy Reising, manager of the California
Department of Water Resources’ snow surveys and water supply
forecasting unit.
Invasive golden mussels have spoiled boating season on the
Sacramento-San-Joaquin Delta after East Bay
Municipal Utility District announced in April the closure of
boat launches in 2025 while the public utility studies the
prevention and removal of the mollusks. EBMUD seeks to prevent
one of the most common ways that golden mussels spread — in
water held on vessels that is then expelled in other waterways
–because if the mussels cross into EBMUD’s infrastructure, they
could clog pipes, pumps, and lead to costly removals.
… Biologists at EDMUD are concerned about containing
golden mussels — the first invasive mussel found in Northern
California — because they are far more adaptable than other
invasive species in California’s waterways, able to survive in
habitats with less calcium and higher water temperatures than
other invasive species like quagga mussels.
Starting Monday, May 19, the Department of Water Resources
(DWR) will require mandatory watercraft inspections at the
Oroville Facilities to combat the invasive golden mussel. The
inspections aim to protect the State Water Project (SWP)
infrastructure. Watercraft inspections will take place at the
North Thermalito Forebay. The inspections are crucial for
maintaining the SWP, which serves 27 million Californians and
supports 750,000 acres of farmland annually. DWR
emphasizes the need to preserve local recreation and will not
close the reservoir. Lake Oroville will remain open, and DWR
encourages early inspections to avoid Memorial Day congestion.
The inspection program will require all trailered vessels and
personal watercraft to have a blue Oroville launch seal. This
seal ensures that the watercraft has not been in infested
waters since inspection.
A new aquatic invader, the golden mussel, has penetrated California’s ecologically fragile Sacramento-San Joaquin Delta, the West Coast’s largest tidal estuary and the hub of the state’s vast water export system. While state officials say they’re working to keep this latest invasive species in check, they concede it may be a nearly impossible task: The golden mussel is in the Golden State to stay – and it is likely to spread.
In the vast labyrinth of the West
Coast’s largest freshwater tidal estuary, one native fish species
has never been so rare. Once uncountably numerous, the Delta
smelt was placed on state and federal endangered species lists in
1993, stopped appearing in most annual sampling surveys in 2016,
and is now, for all practical purposes, extinct in the wild. At
least, it was.
This tour guided participants on a virtual journey deep into California’s most crucial water and ecological resource – the Sacramento-San Joaquin Delta. The 720,000-acre network of islands and canals support the state’s two major water systems – the State Water Project and the Central Valley Project. The Delta and the connecting San Francisco Bay form the largest freshwater tidal estuary of its kind on the West coast.
Nutria are large, beaver-like
rodents native to South America that have caused alarm in
California since their rediscovery along Central Valley rivers
and other waterways in 2017.
The growing leadership of women in water. The Colorado River’s persistent drought and efforts to sign off on a plan to avert worse shortfalls of water from the river. And in California’s Central Valley, promising solutions to vexing water resource challenges.
These were among the topics that Western Water news explored in 2018.
We’re already planning a full slate of stories for 2019. You can sign up here to be alerted when new stories are published. In the meantime, take a look at what we dove into in 2018:
Sixty percent of California’s developed water supply
originates high in the Sierra Nevada mountains. Our water
supply is largely dependent on the health of our Sierra forests,
which are suffering from ecosystem degradation, drought,
wildfires and widespread tree mortality.
We headed into the foothills and the mountains to examine
water issues that happen upstream but have dramatic impacts
downstream and throughout the state.
GEI (Tour Starting Point)
2868 Prospect Park Dr.
Rancho Cordova, CA 95670.
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.
The latest invader is the nutria, a large rodent native to South
America that causes concern because of its propensity to devour
every bit of vegetation in sight and destabilize levees by
burrowing into them. Wildlife officials are trapping the animal
and trying to learn the extent of its infestation.
Estuaries are places where fresh and
salt water mix, usually at the point where a river enters the
ocean. They are the meeting point between riverine environments
and the sea, with a combination of tides, waves, salinity, fresh
water flow and sediment. The constant churning means there are
elevated levels of nutrients, making estuaries highly productive
natural habitats.
A troublesome invasive species is
the quagga mussel, a tiny freshwater mollusk that attaches itself
to water utility infrastructure and reproduces at a rapid rate,
causing damage to pipes and pumps.
First found in the Great Lakes in 1988 (dumped with ballast water
from overseas ships), the quagga mussel along with the zebra
mussel are native to the rivers and lakes of eastern Europe and
western Asia, including the Black, Caspian and Azov Seas and the
Dneiper River drainage of Ukraine and Ponto-Caspian
Sea.
This 24×36 inch poster, suitable for framing, explains how
non-native invasive animals can alter the natural ecosystem,
leading to the demise of native animals. “Unwelcome Visitors”
features photos and information on four such species – including
the zerbra mussel – and explains the environmental and economic
threats posed by these species.
This 24×36 inch poster, suitable for framing, explains how
non-native invasive plants can alter the natural ecosystem,
leading to the demise of native plants and animals. “Space
Invaders” features photos and information on six non-native
plants that have caused widespread problems in the Bay-Delta
Estuary and elsewhere.
The 24-page Layperson’s Guide to the Delta explores the competing
uses and demands on California’s Sacramento-San Joaquin Delta.
Included in the guide are sections on the history of the Delta,
its role in the state’s water system, and its many complex issues
with sections on water quality, levees, salinity and agricultural
drainage, fish and wildlife, and water distribution.
