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
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.
Colorado Parks and Wildlife announced the discovery of an
invasive crayfish species in Lake Granby. The rusty crayfish,
named for reddish spots on its shell, hasn’t been seen in the
state in over a decade. The agency is on high alert because of
Lake Granby’s proximity to the Colorado River, and is now
focused on stopping the crayfish from spreading
further. … Walters said the invaders eat small
fish, insects and fish eggs, which disrupts the aquatic food
web. They can also eat plants on the bottom of the reservoir,
which serve as critical habitat for fish spawning and food for
The California Department of Fish and Wildlife announced the
discovery of an invasive species in Lake Tahoe. According to a
CDFW release, divers monitoring the lake for aquatic invasive
species detected New Zealand Mud Snails (Potamopyrgus
antipodarum) off Lake Tahoe’s South Shore. … They were
believed to have been introduced to western rives through
shipments of live sportfish, but subsequent spread is likely
due to recreational activities, CDFW officials said.
Colorado Parks and Wildlife found an invasive species in Lake
Granby. Multiple rusty crayfish were found at Lake Granby
during routine aquatic sampling on August 17th. According to
CPW, rusty crayfish have been found west of the continental
divide before, but this is the first time they have been found
in the Upper Colorado River Basin. Crayfish are not native west
of the Continental Divide. Lake Granby feeds into the Colorado
River and having the invasive crayfish in there can pose a
threat to the river’s ecosystem.
Jesus Campanero Jr. was a teenager when he noticed there was
something in the water. He once found a rash all over his body
after a swim in nearby Clear Lake, the largest freshwater lake
in California. During summertime, an unbearable smell would
waft through the air. Then, in 2017, came the headlines, after
hundreds of fish washed up dead on the shore. “That’s when it
really started to click in my head that there’s a real issue
here,” says Campanero, now a tribal council member for the
Robinson Rancheria Band of Pomo Indians of California, whose
ancestors have called the lake home for thousands of years. The
culprit? Harmful algal blooms (HABs).
It was the largest algal bloom on record and it took place in
June off the California coast. The planktonic algae made the
water look green while producing a toxin. Seals, sea lions and
dolphins eat fish that have eaten these algae, therefore
hundreds died as a result. … Using satellite data, Gierach
and other scientists created new ways to study the changes in
the ocean. … Satellites can even measure color and
temperature changes. A lot of the increase in algal bloom is
caused by what we dump into the ocean, runoff, fertilizer and
A mosquito breed known for carrying yellow fever and other
diseases has been spotted in portions of the San Joaquin
Valley. Last week, the San Joaquin County Mosquito and Vector
Control District said high numbers of Aedes aegypti mosquitoes
have shown up in traps around South Stockton, Manteca, Escalon
and Ripon. The mosquitoes have also popped up in Butte and
Glenn counties this summer. Like the majority of other
mosquitoes that live here, Aedes aegypti are not native to the
state. They’re also relatively new to California, having first
shown up in traps in 2011, according to the state’s Department
of Public Health.
A popular federal effort to protect threatened Western fish is
in murky waters as stakeholders await Congressional action on
reauthorization. The Upper Colorado River Endangered Fish
Recovery Program has for 30 years sought to restore four
species that once thrived in the river: the razorback sucker,
Colorado pikeminnow, bonytail and humpback chub. A sister
effort, the San Juan River Basin Recovery Implementation
Program, works to restore the same fish in the Four Corners
region. The species are imperiled by human-wrought habitat
disruption, like dams, and preyed upon and out-competed by
introduced species like rainbow and brown trout.
While out enjoying an afternoon on one of Lake Tahoe’s sandy
beaches over the past few years, you might have noticed large
mats of decomposing algae washing up or floating nearby. The
lake’s famed blue waters are facing another threat while the
battles of climate change and invasive species wage on — and
it’s all very much connected. Nearshore algae blooms are
a burgeoning ecological threat to Tahoe. Not only do they
impact the experience for beachgoers, but they also degrade
water quality and, in some cases, pose a threat of
toxicity. Over the last 50 years, the rate of algal
growth has increased sixfold, according to U.C. Davis Tahoe
Environmental Research Center’s 2022 State of the Lake
Grand Canyon National Park will get more than a quarter-million
dollars to remove invasive species and protect native species
of fish in the Colorado River. The funds come from the
Inflation Reduction Act and are part of a nationwide effort to
restore natural habitats and address climate change impacts.
Lake Powell, a key Colorado River reservoir, dropped to
historically low levels last year due to climate change and
drought. This created viable breeding conditions and easier
passage through Glen Canyon Dam for high-risk invasive species
like smallmouth bass and green sunfish.
The Environmental Protection Agency agreed Friday to finalize
nationwide standards that will protect U.S. waterways from the
harmful effects of discharges from ships. Under the agreement,
the EPA must release its final standards on vessel discharges
by Sept. 24, 2024. The standards are required by the Clean
Water Act. The agreement is the end result of a lawsuit filed
by the Center for Biological Diversity and Friends of the Earth
this past February. In their complaint, the groups claimed that
ballast water adversely affects waterways by spreading harmful
zebra mussels, coral diseases and human pathogens. Both groups
were represented by the Stanford Law Clinic.
Today is California Biodiversity Day, which marks the
anniversary of the launch of California Biodiversity
Initiative in 2018 and celebrates our amazing state, the
exceptional biodiversity we have in the Sacramento Valley and
throughout California, and the actions we can work on with our
many partners to ensure biodiversity. In the Sacramento Valley,
our goal is to promote functioning ecosystems and sustainable
water supplies by preserving, sustaining, and promoting our
communities and working agricultural landscapes that support
ecosystem function and provide landscape-scale habitat benefits
for fish, bird, and wildlife populations.
Agencies restoring the Taylor and Tallac marsh areas have
completed the installation of bottom barriers to remove 17
acres of invasive plants as part of the comprehensive
restoration of one of the last natural wetlands in the Lake
Tahoe Basin, the USDA Forest Service Lake Tahoe Basin
Management Unit and Tahoe Regional Planning Agency announced
today. The collaborative project that began in December 2021 is
one of the largest aquatic invasive species control projects
ever undertaken in the Tahoe Basin.
West Nile virus infections are on the rise this year in
California after a particularly wet winter led to more mosquito
reproduction, according to health experts. The state had 55
human cases of the virus as of Aug. 25. Five of them were
fatal, according to the California Mosquito-Borne Virus
Surveillance and Response Program. That’s more than double the
24 cases that had occurred in 2022 by late August of that year.
In total in 2022, there were 207 cases and 15 deaths. Among
California’s latest infections, a woman in Orange tested
positive for the West Nile virus this week, becoming the
first human case in Orange County this year, according to the
county Health Care Agency. The Orange resident wasn’t
experiencing any symptoms.
Water levels at Lake Mohave are expected to drop about 10 feet
in the coming weeks to improve habitat and spawning cycles for
two endangered fish species native to the Colorado River
system. The annual fall drawdown of the reservoir is part of an
ongoing effort by the federal government to restore populations
for the boneytail chub and razorback sucker, the National Park
Service said in a news release. The surface of Lake Mohave will
go from its current elevation of roughly 643 feet above sea
level down to about 633 feet by mid-October. Water levels will
start to tick back up starting in November and return to normal
West Nile virus cases have been increasing in Northern
California. The West Nile virus is the most common and serious
vector-borne disease in the state. There were 29 new West Nile
Virus cases in humans last week, bringing the total for the
year to 55 cases. Those cases have been reported in Glenn,
Lake, Butte, Yolo, El Dorado, Sacramento, San Joaquin, Santa
Clara, Stanislaus, Merced, Madera, Kings, Tulare, Kern, Los
Angeles, San Bernardino and Riverside counties. On Wednesday,
another human case in Roseville became the first this summer in
Placer County. Five people with the virus have died, including
one person in Sacramento County and another person in Yolo
Workers across California are grappling with yet another
climate change-induced threat: a rapidly spreading fungus
that can land its unsuspecting victims with
prolonged flu-like symptoms, or far worse. The culprit is a
soil-dwelling organism called coccidioides, which is now
spreading the disease coccidioidomycosis — known as “Valley
fever” — farther and farther north of its Southwest origins.
Rather than spreading from person to person, Valley
fever results from the direct inhalation of fungal
spores — spores climate change is now allowing to flourish
in new places.
National Park Service biologists planned to close off and
poison a slough connected to the Colorado River upstream of the
Grand Canyon to kill young, non-native bass this weekend, the
agency said. It’s the second time that officials have used
rotenone, a fish-killing agent, as an emergency measure to slow
a mushrooming smallmouth bass invasion from Lake Powell that
threatens native humpback chubs that swim the Colorado farther
downstream. This time they’re seeking hundreds of young bass,
instead of the handful first detected in the slough between
Glen Canyon Dam and Lees Ferry last year.
The National Park Service will renew efforts to rid an area of
the Colorado River in northern Arizona of invasive fish by
killing them with a chemical treatment, the agency said Friday.
A substance lethal to fish but approved by federal
environmental regulators called rotenone will be disseminated
starting Aug. 26. It’s the latest tactic in an ongoing struggle
to keep non-native smallmouth bass and green sunfish at bay
below the Glen Canyon Dam and to protect a threatened native
fish, the humpback chub. The treatment will require a weekend
closure of the Colorado River slough, a cobble bar area
surrounding the backwater where the smallmouth bass were found
and a short stretch up and downstream. Chemical substances were
also utilized last year.
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.
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
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
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
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.