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.
A recreational area in southeastern Sacramento County is
implementing new restrictions to protect its popular lake. It’s
happening at Rancho Seco, in the town of Herald. New watercraft
restrictions are now in effect to stop the spread of golden
mussels recently discovered in the Sacramento-San Joaquin
Delta. Signs around Rancho Seco alert people to the invasive
species, saying, “Don’t move a Mussel.” No trailer-launched
boats are allowed on the lake. People can still use small
watercraft like canoes, kayaks, paddle boats, and smaller
electric watercraft, but only if they haven’t been used in
other waterways, including the Delta, within 30 days.
The Solano County Water Agency’s free vessel decontamination
program will end on April 7. … The Bureau of Reclamation
announced that, beginning April 7, direct-managed concessions
and the Solano County Water Agency will charge for vessel
decontaminations for boaters seeking to launch at Lake
Berryessa. … “Moving forward, boaters who seek to avoid a
30-day, mandatory quarantine to protect the reservoir
from invasive mussels, will need to reach out to
either the Solano County Water Agency, Markley Cove Resort,
Pleasure Cove Marina, or Putah Canyon Recreation Area to
arrange for a vessel decontamination for any motorized vessel
or vessel launched from a trailer,” the Bureau of Reclamation
announcement states.
California’s most-destructive and least-welcome swamp rodents
have arrived in its fifth-largest city. To be precise, they’ve
arrived in the stretch of San Joaquin River that traces
Fresno’s northwest border. Eight years have passed since a
reproducing population of nutria was found in western Merced
County — their first discovery in the state since the 1970s.
Despite eradication efforts that began in March 2018, nutria
have since spread north into the Delta, east into foothills
along the Merced River and south into the Fresno Slough and
Mendota Wildlife Area. … Since 2023 more nutria have been
taken from Fresno County than any county in California,
according to CDFW data. In the overall tally of 5,493 animals
that dates to 2018, Fresno County (1,140) trails only Merced
County (2,593). -Written by Fresno Bee columnist Marek Warszawski.
… Nutria are rodents native to South America, but they are
causing a headache for crews in California. … Crews are now
getting help from outside the state. The Sacramento-San Joaquin
Delta Conservancy supplied an $11 million grant to bring in
detection dogs from the East Coast. The dogs are experts at
finding nutria scat, which helps find the best area for DFW
crews to set traps. Congressman Josh Harder has backed bills
authorizing federal funds in the fight. “These nutria cost
places like Louisiana hundreds of millions of dollars every
year in infrastructure losses,” Harder said. “That’s going to
happen to California if we don’t get this eradicated.”
California State Parks’ Division of Boating and Waterways (DBW)
announced today its 2025 control efforts for invasive aquatic
plants in the Sacramento-San Joaquin Delta and its southern
tributaries (Delta). Starting March 20, DBW will begin
herbicide treatments on water hyacinth, South American
spongeplant, Uruguay water primrose, alligator weed, Brazilian
waterweed, curlyleaf pondweed, Eurasian watermilfoil, coontail,
fanwort, and ribbon weed in the Delta. The treatment start date
may change depending on weather conditions and plant
growth/movement. … These aquatic invasive plants have no known
natural controls in the Delta, the West Coast’s largest
estuary. They negatively affect the Delta’s ecosystem as they
displace native plants that are essential to the area’s
biodiversity while negatively impacting the economy,
environment and public health.
Wildlife officials are encouraging California residents to add
a rodent to their daily diet as part of efforts to control the
invasive species’ population. The nutria, a large, semi-aquatic
rodent native to South America, is threatening the state’s
ecosystems by destroying habitats and outcompeting native
wildlife. The nutria’s harmful impacts have prompted wildlife
officials to promote hunting and consumption as possible
solutions. … To mitigate their impact, CDFW has removed
about 5,500 nutria from California wetlands as of early
February. The highest concentration of these rodents were found
in Merced, Fresno, Stanislaus and Solano counties.
… (I)f (Rep. Josh Harder) wants to enlist the public’s help to
turn the tide against invasive species with the potential to
destroy the Delta, he might want to consider adding invasive
bass to his list. The Pacific Marine Fisheries manages the
Northern Pikeminnow Sport Reward Program that has been in place
on the Snake and Columbia rivers since 1991 in Oregon and
Washington. … The program in Oregon and Washington
gives credence to the potential effectiveness of a plan batted
down in Sacramento 12 years ago to save the threatened salmon
and steelhead. The plan was an aggressive cutback on the
non-native bass that are huge consumers of the native salmon
and steelhead as well as the almost extinct Delta smelt. –Written by Manteca Bulletin editor Dennis Wyatt.
Invasive species such as zebra, quagga, and now golden mussels
have become a significant financial burden in the United
States, with prevention and control efforts costing an
estimated $6 billion since 1988. The Nevada Department of
Wildlife has raised concerns about the potential impact of
these species on local ecosystems, particularly if zebra or
quagga mussels were to invade Lake Tahoe. The estimated
financial impact of such an invasion could exceed $20 million
annually.
Federal wildlife officials are promoting a unique strategy to
help eliminate nutria, the pesky critters that have invaded
California’s Delta: Eat ’em. Turns out that nutria, a giant
rodent that looks like an outsized guinea pig, can be a
mouth-watering entree. “Their meat is lean, mild and tastes
like rabbit,” the U.S. Fish and Wildlife Service says, urging
the consumption of nutria and four other bothersome invasive
species. Nutrias have been particularly troublesome in the
Delta because they can reproduce quickly and are tearing up the
marshlands. A single female can birth up to 200 offspring in a
year, and their burrowing causes erosion of riverbanks. Plus,
they have a voracious appetite. A single nutria can consume up
to 25% of its body weight in vegetation a day.
Boat launches at all East Bay Municipal Utility District
reservoirs will remain closed in an effort to keep invasive
golden mussels from infesting the public water supply, the
agency said. Golden mussels haven’t been detected in EBMUD’s
seven raw water reservoirs, and the boat launch closures
announced this past Thursday are a pre-emptive measure to keep
them at bay. Last October, the invasive bivalves were
discovered in the Sacramento-San Joaquin Delta — the first
known occurrence of the species in North America, according to
the California Department of Fish and Wildlife.
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.
