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.
… On [peach farmer Rob] Talbott’s farm, water pumps move
almost 200 gallons per minute to the thirsty crops on his 145
acres. This year, a new threat is approaching that water
system. And it’s microscopic. Invasive zebra
mussels have now infested at least 135 miles of the
Colorado River, from the Utah border to Dotsero in western
Colorado. That includes the stretch that meanders alongside
Talbott’s orchards in Palisade. And if these tiny pests flow
into his narrow irrigation pipes and tubes, they threaten to
mature and block his most precious farming ingredient. These
mussels rapidly multiply. A single female lays up to 30,000
eggs. And when they reach adulthood, their sharp shells can
wreak havoc on water infrastructure.
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.
When Colorado Parks and Wildlife personnel tested a small pond
that feeds the irrigation system at the Mesa County
Fairgrounds, looking for invasive zebra mussels, the results
came back as a surprise. … Mussels of different ages,
including adult ones, were discovered during the early-October
testing. … It seemed more likely that mussels might be
present at some of the public areas along the Colorado
River or on larger reservoirs with a lot of potential
for cross-contamination involving things such as watercraft.
… This very issue is high on the minds of Parks and Wildlife
officials as the agency deals with an expanding zebra mussels
problem along the Colorado River in multiple counties.
A rapidly growing infestation of invasive golden mussels is
raising concerns among engineers, boaters, and water agencies
as the species spreads through the Sacramento–San Joaquin
Delta. … So far, crews have resorted to scraping pipes
by hand or using pressure-washing equipment. Some agencies are
testing ultrasonic or electronic systems that discourage marine
growth, but there is no proven long-term solution.
… Local boaters and maritime experts are raising the
alarm over the rapid spread of golden mussels in the
Sacramento-San Joaquin Delta, warning of rising maintenance
costs and potential risks to water infrastructure.
The invasive pest spotlight focuses on emerging or potential
invasive pests in California. In this issue we are covering
nutria. The nutria is a large semi-aquatic rodent
introduced to California in the early 1900s to be farmed for
their fur. … Nutria have since spread into waterways
within the Sacramento-San Joaquin River Delta and the Central
Valley. … Nutria severely damage the environment,
roads, levees, and crops. They burrow into banks of waterways,
weakening or collapsing them. As they feed, they damage the
native plant communities and soil structure of wetlands. Nutria
feeding and burrowing damage both increase the risk of erosion
and flooding.
For years, farmers have struggled with water supplies.
Sometimes, because of drought. Other times, because of
government red tape. But now, they are facing a new threat that
requires all hands on deck— from laboratories to the
legislature. “The potential impact is significant,” says Kelly
Vandergon, Deputy General Manager for Operations and
Maintenance at Westlands Water District. FOX26 was there
Friday, as crews carried out maintenance on a pump near Five
Points along the California Aqueduct. As they removed the
traveling water stream pump you could see shell after shell–
Golden Mussels— attached to the pipe.
Colorado Parks and Wildlife has expanded the area of the
Colorado River labelled “infested” with zebra mussels. The area
extends from the confluence of the Eagle River down to the
Colorado-Utah border. The designation comes after CPW sampled
four Western Slope rivers — the Eagle, Gunnison, Roaring Fork
and Colorado rivers — on Oct. 29. The Yampa River feeds the
Colorado through the Green River, and faces threats of its own,
apart from zebra mussels. …. Of the five main aquatic
nuisance species closely monitored by CPW — Eurasian
watermilfoil, New Zealand mudsnails, quagga
mussels, rusty crayfish and zebra mussels — only the crayfish
is identified in the Yampa, and has been since 2009.
Boat launches at two East Bay Municipal Utility District
reservoirs will reopen in 2026 on a limited basis, following a
yearlong closure aimed to stave off the invasive golden
mussel. The reopening plan was approved last week by the
EBMUD Board of Directors for the San Pablo Reservoir in the
East Bay and the Camanche Reservoir South Shore in the Sierra
foothills. … The destructive species hasn’t been
detected at any of EBMUD’s reservoirs, but the golden mussel
has spread quickly throughout the state since it was first
identified in the Sacramento-San Joaquin Delta in October 2024.
… EBRPD [East Bay Regional Park District] changed its boat
inspection and banding policies back in May to help protect its
waterways from the golden mussel, instituting new color-coded,
lake-specific, tamper-proof bands and no longer accepting
EBMUD’s [East Bay Municipal Utility District] bands. Boats
without a band for that specific waterbody had to go through a
full inspection and pay a fee, each time. … The change
seems to have largely worked, with an asterisk in Antioch. …
[T]he critter was found in Contra Loma Reservoir, so boats that
have been in that lake must stick there only or complete a
30-day quarantine. Meanwhile, a half-inch-long juvenile
golden mussel was recovered at Zone 7’s Patterson Pass Water
Treatment Plant this year.
Voracious, invasive zebra mussels hopped an upstream ride over
the summer and added 100 miles of Colorado River to their
fast-growing infestation of state waterways, Parks and Wildlife
officials said after a recent multiagency, multicounty
sampling. Previously pegged in the Grand Junction area, the
Oct. 29 sampling and subsequent analysis found adult zebra
mussels upstream in Glenwood Canyon and all the way up to the
Colorado River’s junction with the Eagle River at Dotsero, near
a private lake treated for zebra mussels in August.
When it comes to zebra mussels in the Colorado River system,
Colorado Parks and Wildlife Director Jeff Davis summed it up
this way: “We look, we find.” While Colorado’s first
detection of the highly invasive zebra mussel was in 2022,
Parks and Wildlife, alongside federal and local partners, has
ramped up testing for the species following a growing number of
finds this summer on the Western Slope. … Zebra mussels
are an invasive aquatic species notorious for their prolific
reproduction and destruction of ecosystems and
infrastructure.
Hyacinth, an invasive and seasonal plant, is once again
invading Stockton waterways. This year’s bloom came into
downtown Stockton from the Tuolumne River, breaking off during
the last storm. … ”If you can’t have a bar pilot enter
the ship from San Francisco Bay and come upstream because their
radar is showing large mats of hyacinth, they pretty much call
Stockton and West Sacramento saying we’re gonna have to drop
anchor because we cannot distinguish between land and the
weeds,” California State Parks Boating and Waterways
Environmental Program Manager Edward Hard explained. Hyacinth
also brings mosquitoes [and affects] water
conveyance.
Stockton’s downtown waterfront faces an annual takeover by
invasive water hyacinth, a fast-growing plant that can blanket
thousands of square feet of water in a single season. Deemed
“hopeless” by PBS in 2015, the plant returns each year to San
Joaquin County waterways, including McLeod Lake in Stockton,the
Calaveras River and the broader Sacramento-San Joaquin Delta.
Known as “the fastest-growing plant in the world,” a single
hyacinth can wreak massive ecological and economic damage,
making it one of California’s most destructive invasive
species. Unlike other invasive plants, experts say eradication
is nearly impossible, leaving ongoing control as the only
viable solution.
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.
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.
