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.
California State Parks’ Division of Boating and Waterways (DBW)
today announced the availability of grant funding to help
prevent the further spread of quagga and zebra mussels that
threaten California’s waterways and cause negative impacts to
recreational boating, fishing and the ecosystem. Funded by the
California Mussel Fee Sticker (also known as the Quagga
Sticker), the Quagga and Zebra (QZ) Mussel Infestation
Prevention Grant Program expects to award up to $2 million
across eligible applicants. Applications open Monday, March 9,
and must be received by Friday, April 17, 2026, by 5 p.m. PDT.
Following the discovery of invasive zebra mussels in the
Colorado River last year, Colorado Parks and Wildlife (CPW) is
working hard to prevent further contamination across the
state. Part of that is an ongoing effort in boat
inspections to prevent the spread of invasive aquatic species
including both zebra and quagga mussels. In 2025, CPW conducted
more than 438,000 such inspections at various bodies of water.
Officials say early detection of the invasive species was made
possible by increased staffing and upgraded lab facilities, but
the discovery on the Western Slope still set off alarm bells
because once adults are present in a reproductive state, they
have the ability to rapidly multiply and clog
infrastructure.
In the cool dawn of a February morning, a crew is assembling to
do maintenance work on a water canal in Tempe. This crew will
spend the rest of its life in the canal, removing the plants
that stop water from flowing. That’s because the workers aren’t
human — they’re fish. The Salt River Project, which operates
this canal, estimates that about 44,000 of these fish live in
its canal system. This morning, it’s adding about 1,000 more.
The fish are a species of carp called white amur. They’re
native to Asia and especially adept at eating the aquatic
vegetation that grows along the walls of the canal. Those
plants can slow down the water and make it harder to send to
faraway users of the canal or gum up the intakes that divert
water in different directions.
Officials are sounding the alarm over an invasive species
threatening one of California’s key water systems. Golden
mussels, first detected in the Friant-Kern Canal two months
ago, are rapidly multiplying and could disrupt water delivery
to farms and communities in the southern San Joaquin Valley.
The Friant Water Authority held a board meeting Thursday to
address the infestation and outline next steps. The board voted
to hire a consultant to develop a comprehensive control plan,
though any treatment would require permits and could take
several months. The agency is also seeking grants to help fund
prevention and control efforts.
Colorado Parks and Wildlife staff conducted more than 438,000
watercraft inspections in 2025 to prevent the spread of
invasive species in state waters. The agency decontaminated
more than 30,000 high-risk boats and intercepted 136 vessels
carrying invasive mussels during the year-long effort. The
inspections are part of a statewide prevention program designed
to protect water infrastructure from destructive aquatic
nuisance species. … In 2026, staff will install a
decontamination dip tank at Highline Lake to reduce wait times
for departing boaters. The agency also plans to partner with
federal and local groups to sample Grand Valley ponds and lakes
that receive water from the Colorado River.
The Arvin-Edison Water Storage District and Wheeler
Ridge-Maricopa Water Storage District boards both agreed
recently to spend $2.5 million and $2 million, respectively, on
efforts to rid their systems of invasive golden
mussels. At its Feb. 10 meeting, Arvin-Edison’s Resource
Manager Samuel Blue laid out a two-phase attack against the
mussels. First, Blue plans to start with a chemical treatment
called Natrix CA in March, when there is less water demand by
district farmers and the temperatures are cooler. The mussels
are more active in warmer water, Blue explained. He hoped the
treatment would kill off 90%, or more, of the adult golden
mussels.
The time to act on golden mussels is yesterday. If not
yesterday, then now, an expert on invasive mollusks told
attendees at the World Ag Expo in Tulare Wednesday. … These
things are “quagga mussel on steroids” said David Hammond, a
senior scientist at Earth Science Labs. He urged irrigation and
water district managers at the seminar to enact immediate
preventative measures, or their entire conveyance systems would
be at risk of being overrun by the tiny, rapidly multiplying
mussels. … Golden mussels, native to Southeast Asia and
a cousin to quagga and zebra mussels, were first discovered in
the Sacramento-San Joaquin Delta in 2024. And in less than a
year, have traveled the length of the state, clogging
infrastructure as they rapidly multiply.
When the golden mussel was discovered near the Port of Stockton
in late 2024, lakes and reservoirs across Northern California
imposed new rules on boaters to try to keep the invasive
species out. EBMUD, the water supplier for most of the East
Bay, took no chances, banning all boats from entering its
reservoirs. On Sunday, after more than a year, they began
inviting boats back to the water, but they’re being very
careful about it. … EBMUD has decided the most effective
action is a 30-day quarantine. After an inspection to be
sure they’re completely clean and dry, boats will be tethered
to their trailers with sealed cables to prevent them from being
launched. After the waiting period, they will be allowed back
on the lake and then, upon leaving, given another sealed
tether, specific to San Pablo.
If the golden mussel invasion that already is
expanding throughout much of California hits the Eastern
Sierra, the damage it will bring will ripple far beyond
recreational fishing, according to state officials. Nick
Buckmaster, an environmental specialist with the California
Department of Fish and Wildlife, told the Inyo County Board of
Supervisors Tuesday that the invasive species is “amazingly”
resilient and that its adaptability makes it effectively
impossible to eradicate.
The golden mussel, an invasive species that is making its way
across the delta, through waterways and pipes, is now
reaching as far south as Riverside County. … On
top of concerns that farmers won’t be able to pump water during
the dry months, it also poses a flooding threat to urban areas.
… Action is already being taken at the county and state
levels. The San Joaquin County Board of Supervisors created a
local golden mussel committee to help communicate better with
state and affected areas in the county. The state has also
secured $20 million in this year’s budget to combat the spread
and support local prevention efforts. In the meantime, these
small invaders are here to stay.
Water agencies of all sizes are crafting plans and forming task
forces across local, state and federal entities to protect
infrastructure from the spread of golden mussels, a tiny,
invasive species that has already spread the length of the
state’s network of waterways. In the San Joaquin Valley,
Friant Water Authority is in the midst of another round of
environmental DNA testing, this time on the entire length of
the 152-mile canal, after golden mussel eDNA was detected near
the White River intake in Tulare County. Initially, the
authority hoped the mussel was contained to the southern
reaches of its canal, in the Arvin-Edison Water Storage
District, where State Water Project supplies enter the Friant
system via the Cross Valley Canal.
A Lake Tahoe boater is facing thousands of dollars worth
of fines after an alleged violation posed a threat to golden
mussels. According to the California Department of Fish
and Wildlife, the boater “tried to skirt Lake Tahoe’s boat
inspection and found out the hard way how seriously the threat
of golden mussels is being taken.” CDFW said the Tahoe
Regional Planning Agency discovered that the boat had a
tampered inspection seal and was recently launched at Folsom
Reservoir. The boater was fined $5,000.
Attention Western Slope pond owners: Colorado Parks and
Wildlife is on the hunt for hungry, fast-reproducing, invasive
mussels — and that they might be hiding in your pond.
State and federal agencies, plus water districts, are fighting
to track and contain zebra mussels in and around the Colorado
River in Colorado. Officials are hiring new staff, doing
sampling blitzes and catching mussel-bearing motorized boats at
the state’s borders, but the populations of zebra mussels keep
popping up. This year, the state is taking its search beyond
public waters and irrigation systems. Colorado Parks and
Wildlife staff hope to survey as many as possible of the
thousand-plus ponds on private property in the Grand Junction
area during summer 2026.
Colorado’s expert on aquatic invasive species said Wednesday
the state has an “incredible fight ahead” as it works to
contain the spread of zebra mussels in the Colorado River. “I
wish I could tell you the story of zebra mussels has
concluded,” Robert Walters told a crowd of dozens of water
professionals at the Colorado Water Congress in Aurora.
… He said this year’s strategy includes ramping up
testing of hundreds of ponds in the Grand Junction area. “There
is vast network of canals, ditches and washes moving this
water,” he said. “Golf courses, people with ponds in their
backyards. Everyone who is receiving Colorado River water has
the potential to be harboring these highly invasive mussels.”
On Tuesday, February 3, the Inyo County Board of Supervisors
will host a workshop to discuss how to address the significant
threat to our local environment and economy posed by the Golden
Mussel. … Without active efforts to educate the
visiting public about this threat and a mandatory inspection
and decontamination requirement for boats, it is highly likely
that the Golden Mussel will be introduced into the Eastern
Sierra watersheds. … Given the looming threat, Inyo
County staff engaged with Mono County, CDFW, the Town of
Mammoth Lakes, the Inyo County Fish and Wildlife Commission,
the Los Angeles Department of Water and Power, Southern
California Edison, the City of Bishop, and the Inyo County
Sheriff and District Attorney, to consider how the numerous
parties can work collaboratively to help prevent the
introduction of the Golden Mussel to regional waterways.
The fight to remove the golden mussel continues in California.
The invasive species is damaging boats, clogging pipes, and
threatening water systems across the state, according to the
San Joaquin Farm Bureau. … Here at home, they have been
detected in the San Luis Reservoir and the Friant-Kern Canal.
These invasive species are causing frustration and costly
concerns throughout the state. … A reservoir in the East
Bay remains closed to boats because of the golden mussel
spread, and experts say more could close as they try to come up
with a solution.
… California relies on a patchwork of local rules — like
“dry-out” periods that require boaters to wait before using new
waterbodies — to ward against the proliferation of invasive
aquatic species. These measures frustrate recreationists and
hurt rural economies. And, unfortunately, they have not stopped
the spread. … California must shift from a “closed-gate”
model to active suppression and coordination. We can use
promising tools — like UV disinfection systems and copper-based
treatments — to kill larvae at major water hubs before they
reach rural systems. These investments protect infrastructure,
fisheries and recreation economies. –Written by Calaveras County Supervisor Amanda
Folendorf.
Invasive golden mussels have now been found in the Wheeler
Ridge-Maricopa Water Storage District system, Engineer Manager
Sheridan Nicholas reported at the board’s Jan. 14 meeting. This
was the first detection for the district. … Nicholas
told the board that he had informed the Kern County Water
Agency about the mussel discoveries and urged that board to
create a region-wide task force as many districts are finding
the equipment- and pipe-clogging critters but fighting it
individually. At the Kern County Water Agency’s Jan. 22
meeting, staff confirmed they are creating a task force to
include local water districts as well as others that receive
water through the Central Valley Project that extends to
Millerton Lake.
The 24-page Layperson’s Guide to the Delta explores the competing
uses and demands on California’s Sacramento-San Joaquin
Delta. The 11th edition examines this critical
water hub and its myriad challenges. The 2025 version
includes the latest information on the tunnel project, habitat
restoration efforts, climate change impacts and an updated
section on the legal and political facets of the Delta.
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 form highly productive natural habitats due to a
combination of tides, waves, salinity, fresh water flow and
sediment.
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.
