A daily compilation of significant news articles and comment
March 25, 2008
3. Watersheds
Is warming a clear danger for Tahoe?; The lake's jewel-blue waters may get murky as greenhouse gas emissions alter its ecology, scientists say -
Warming could hurt Tahoe fish, plants within decade - Reno Gazette Journal
Future of Lake Tahoe looks murky, study says; UC Davis researchers predict climate change will cause permanent damage - Inside Bay Area
SALMON RUNS:
Butte Creek salmon to be strong - Paradise Post
Salton Sea Authority begs local governments for funding - Desert Sun
Is warming a clear danger for Tahoe?; The lake's jewel-blue waters may get murky as greenhouse gas emissions alter its ecology, scientists say
By Eric Bailey, staff writer
SACRAMENTO -- -- Global climate change may be causing a pivotal shift in the depths of Lake Tahoe that could fundamentally alter its ecology by the end of the next decade and turn its famed jewel-blue waters a murky hue, according to a recent study.
The research and computer modeling by scientists at UC Davis predict that warming could limit the lake's natural mixing cycle, disrupting the food web and potentially robbing it of the clarity that has helped make Tahoe a world-class tourist destination.
Experts from the university's
But the most visible shift could be to its waters, which have inspired awe since the Gold Rush days, earning Tahoe the nickname "Jewel of the Sierra."
Those waters have been losing clarity as urban development carpeted the basin, prompting a crash government effort to stem the effect of runoff. The Tahoe region now has some of the toughest development and environmental rules in the world.
The latest threat to the lake, however, stems from the far more intractable problem of worldwide greenhouse gas emissions and a warming globe.
"Tahoe is another victim," said John Reuter, the center's associate director and one of the report's authors. "The world views the lake as a pristine place, a refuge. When you hear global warming is affecting Tahoe, is anywhere safe? The answer is no."
Tahoe residents working for years to save the lake said the study underscored the broad urgency of their fight.
"We're not ready to decide that the solutions are out of our hands," said Rochelle Nason, Keep Tahoe Blue executive director. "We remain optimistic we can protect the lake. But ultimately, the climate change issue will have to be addressed if we're going to succeed in the long term."
Reuter and the study's other authors, the center's director Geoffrey Schladow and postdoctoral researcher Goloka Sahoo, presented their findings last week at a Tahoe scientific conference.
A warming trend has been underway at the lake for at least 40 years. Although the surface water temperature has risen a single degree, Reuter said that was as significant as a one-digit change in the human body.
In the case of the lake, that means oxygen-rich surface water that was reliably churned into Tahoe's 1,644-foot depths every four years is now less apt to circulate. Nutrients carted upward and oxygen cycled downward would ebb.
In the worst-case scenario, the study found, the mixing could halt entirely by as early as 2019, a time frame that Schladow said "was very surprising."
If it happens, ecological fallout could come quickly.
"Then it's not a matter of if, it's a matter of when," Reuter said.
Lake trout and other native fish would be forced to huddle in areas that still prove habitable. Phosphorous locked in the lake's bottom sediments would be released, fueling algae blooms on the surface.
That could combine with other factors, such as particles in shoreline runoff, to rob the lake of clarity, turn the air foul and produce bad-tasting drinking water, the scientists said.
Many lakes in
The scientists are part of a half-century effort to study the lake, focusing on the causes of Tahoe's declining clarity. UC Davis researchers reported the lake's warming trend in 2004, and Schladow's team built on those findings using a computer model that combined air temperatures, cloudiness and wind speed to determine scenarios for the traditional mixing cycle.
Reuter said the scientists felt most certain about the potential effects on fish and other aquatic life. Less clear is how warming-induced changes will influence Tahoe's cobalt-blue color, he said. If the bottom phosphorous is released, the lake could quickly turn from blue to green.
Lake Tahoe is one of many in the world seeing warming waters, among them
http://www.latimes.com/news/local/la-me-tahoe25mar25,1,3248016.story
Warming could hurt Tahoe fish, plants within decade
By Jeff DeLong, staff writer
Within a decade or so, a changing climate could warm
New findings by researchers from
"A permanently stratified
The study, announced during an ongoing seminar at the center, follows another study conducted in 2004 that concluded Tahoe's waters warmed slightly less than 1 degree over a 33-year period ending in 2002. Tahoe's warming was about twice the levels recorded for the world's oceans and likely was tied to global warming, researchers found.
The latest research combined 40 years of weather data collected in the
The latest study suggests that if global greenhouse gas emissions continue at current levels, mixing could become less frequent, occur only at shallower levels or even stop completely as soon as 2019.
"While we expected that the lake would mix less in the future, learning that we may be only a decade or two from the complete shutdown of deep mixing was very surprising," Schladow said. "If mixing shuts down, then no new oxygen gets to the bottom of the lake, and creatures that need it, such as lake trout, will have a large part of their range excluded."
A warmer lake would support fewer cold water fish but encourage the spread of invasive species. Warm water fish, including large-mouth bass, bluegill and carp, are already showing up in Tahoe's waters in increasing numbers.
Another worrying possibility, Schladow said, is that the depletion of oxygen could result in the release of phosphorus currently locked up in lake floor sediments. Phosphorus could rise to the lake's surface and encourage growth of algae, which along with suspended sediments is resulting in continuing loss of Tahoe's famed clarity.
Schladow said researchers are continuing to explore whether lowered global greenhouse gas emissions could slow or prevent problems at Tahoe believed connected to climate change. #
http://www.rgj.com/apps/pbcs.dll/article?AID=/20080325/NEWS04/803250333/1321/NEWS
Future of
Inside Bay Area – 3/25/08
By Julie Sevrens Lyons, MEDIANEWS staff
The jewel of the Sierra could be worse off than previously thought.
In a new study, researchers at UC Davis predict that climate change will irreversibly alter water circulation in
Global warming already is causing warmer lake temperatures along the shoreline, and it is likely to continue to cloud up the cobalt waters that attract tourists from all over the world. However, the most recent news came as a shock to even the researchers.
"This is one of the early indicators of what climate change can do to freshwater supplies nationwide," said Geoffrey Schladow, director of the
At stake is the lake's fragile ecosystem, with scientists expecting that climate change will affect the chemistry of the lake by preventing its many layers of water from mixing, depleting the bottom levels of oxygen. Some types of fish will need to move to shallower waters in the 1,644-foot-deep lake, where they will be threatened by non-native and, in many cases, aggressive fish such as the largemouth bass that has already appeared along the Tahoe Keys.
"The biggest immediate impact from that is if this happens over the course of decades, we may lose a lot of the valuable trout and cold water fish habitat," said John Reuter, associate director of the UC Davis Tahoe Environmental Research Center. He is one of several scientists who presented the new findings at a scientific conference in
The lake is made up of many layers of water, with the surface being rich in oxygen. When the wind is right and temperature is ideal, the top layer sinks, and in the best years goes to the bottom. This is not a constant process, but it happens, on average, about every four years, usually in late February.
Through the process, oxygen from the surface is distributed throughout the lake, benefiting plants and fish at the bottom that are dependent upon it to survive, especially trout.
Through extensive computer modeling, the scientists determined that the deep mixing may not occur as frequently in the future because of global warming. By 2019, it might not occur at all. The finding, Schladow said, came as a complete surprise.
The wintertime process is important as the churning about of water also dilutes all the contaminants that came into the lake the previous spring. Deep mixing also moves nutrients from the lake bottom to the water surface, where they promote the growth of algae.
"If greenhouse gas emissions continue at their present levels, there are pretty big changes in store for the lake itself, for its mixing environment and water quality within the next 10 to 20 years," Schladow said. "This brings home the urgency of the need to reduce emissions."
The scientists said it is still unclear whether a failure of the layers to mix would hurt the clarity of the lake.
But they know that as temperatures rise, less snow and more rain is falling in the Sierra, fueling soil erosion and contributing to the ever-increasing murkiness of the waters.
This past summer, scientists demonstrated that global warming already is affecting the
Just since 1999, the average July surface water temperature of the lake has increased almost 5 degrees, with temperatures near the shoreline hitting a record 78 degrees on July 26, 2006.
The lake's clarity also has diminished over the years. While visitors to the lake could see down an average depth of 102.4 feet in 1968, by 2006 visibility extended to an average depth of just 67.7 feet, a decline of about one foot per year.
The new data suggesting that the warming of the lake may help invasive fish species while harming native fish is just another nugget of bad news, said Carl Young, program director of the League to Save Lake Tahoe, an environmental advocacy organization aimed at protecting the health of the
"All these things look very foreboding," he said. "The future holds significant challenges to help preserve the jewel of the Sierra." #
SALMON RUNS:
Butte Creek salmon to be strong
By Paul Wellersdick, staff writer
Despite salmon numbers dwindling from the northern Oregon border throughout California and proposed fishing bans in the states, Butte Creek may have abundant salmon, maybe even too many.
Allen Harthorn, executive director of Friends of Butte Creek said fishing was closed in 1994 by the California Department of Fish and Game, but re-opening salmon fishing would help reduce numbers to a manageable level.
"The whole idea behind this is that the Department of Fish and Game and PG&E that operate the Centerville Powerhouse, say there's too many fish," Harthorn said.
"I've been telling them that if there is too many, then anglers should help thin the population," he said.
Putting a hard number on how many fish the habitat can support is tough for DFG to do, but 9,000 salmon have been counted in the habitat, and biologists claim there's only habitat for 6,000, Harthorn said. Chinook, the variety of salmon in Butte Creek, are a threatened species and because of that, "there won't be any fishing for quite some time," he said. The lack of fishing will certainly hurt the economy, Harthorn said. Harthorn said each fish caught could bring in $500 for the local economy.
Rocque Merlo owner of
"Everybody stays at a hotel and eats at the Fifth Street Steakhouse and buys equipment."
This year's season may be short or non existent and the legal limit of fish able to be caught has yet to be set.
Three options were proposed by DFG last Thursday, March 20 and are posted at www.dfg.ca.gov. In
The business has changed rapidly,
Recently salmon numbers for fall run fish are low and may hurt business. More than anything,
"You definitely shouldn't be jigging," he said.
Jigging is a technique using long, slender, two ounce pieces of lead with treble hooks to attract fish. It can hurt fish by snagging.
"That's when the striper come out and wipe out the Salmon," he said. "Stripers are at an all time high in April and May"
Though numbers are low for fall run salmon fish populations, Butte Creek may be nearing 17,000 now,
"Now it puts PG&E on the line,"
The bigger story, for Harthorn is that hatchery fish can't handle the harshness of the wild as well as natural fish, he said.
"I don't have enough knowledge to say, but I don't think so," he said. "They're not genetically modified. I can't see why that'd be different. I just go by what I see, but something is off, three or four years ago it was phenomenal out there."
Harthorn said the dramatic decrease in salmon population is found in the fall run of the fish, not in the spring run. Salmon are migratory fish that live in the ocean part of their lives. Their run is when they return to rivers and creeks to spawn. Fall run fish populations decreased 80 percent from 2006 to 2007, Harthorn said.
During that same time, Butte Creek Chinook salmon numbers increased from 6,400 more than 6,800. Butte Creek salmon are all wild, naturally spawning salmon, spring run fish, he said.
"From the minute they come out of the gravel they're surviving in the wild."
He compared that to hatchery fish.
"They're herded like cattle into the spawning room that's another unnatural process that leads to less genetic strength."
Spring run was the largest population of salmon prior to the construction of dams because rivers and creeks have the highest flows in the spring and fish could get farther into the waters into cooler water to survive the summers, Harthorn said. The way to solve the problem is to truck the migrating fish around the dams or to build fish ladders for the fish to migrate with, Harthorn said. The problem with those solutions is that they cost a lot of money.
Bill Zemke, senior licensing coordinator with PG&E said PG&E filed its re-licensing application last October and is now waiting on a response from FERC. A FERC license for the powerhouse is good for 30 years and also covers the West Branch of the
Curtis Steitz, a PG&E biologist said Butte Creek has several runs of fish, but the most emphasis is on the spring run of the Chinook salmon that starts now and peaks in April.
It is hard to estimate populations right now, because the flows are so high and the water is murky. Numbers won't come in until April, Steitz said. The Department of Fish and Game uses two ways to count the fish. One is to snorkel the creek with three or four people using only direct observation. The other is to count fish carcasses in the fall, he said.
The low numbers of salmon talked about in the media now are the fall run of the salmon which accounts for most of the commercial and sport fishing. He agreed with Harthorn's theory that historically, the spring run was the dominant run before dams and said Harthorn's numbers are close. Looking at the carcass count numbers alone, they show 6,303 in 2006 and 6,214 in 2007, but the numbers are too close, statistically to differentiate an increase or decrease.
Steitz said most hatcheries produce fall run fish, and there is a wild component of fall run but they outnumbered by hatchery fish. Are the natural fish a stronger breed?
"That is certainly discussed a lot in the scientific community. Some studies suggest it, others are not that definitive," Steitz said. "Most people would want to and tend to believe they are."
As part of re-licensing, PG&E studies the potential for fish ladders and screens, but no one has made any proposals for ladders, or trucking. The numbers of fish won't affect PG&E's operation.
"It doesn't affect us one way or another, because it is a protected species, it does affect the way we handle that," Steitz said. "Whether there's a small run or not we'll operate the same way and try to maximize the cool water benefits no matter what the return is." #
http://www.paradisepost.com/ci_8682979
Desert Sun – 3/25/08
By Keith Matheny, staff writer
Salton Sea Authority members are asking the local governments they represent to toss the group a life preserver - more money to keep it afloat.
The authority projects it will have only $97 in available funds by the end of April.
"It will allow us some clerical support," said Supervisor Roy Wilson, an authority member.
Other authority members, including the Coachella Valley Water District,
"It should get us through another six months or so while we assess what the state is going to do,"
The Coachella Valley Water District's board approved $25,000 for the group last week.
IID's board has yet to act on the additional payment, "but more than likely when it does (come up), we will approve it," district board president John Pierre Menvielle said.
The
Fish and bird habitat could be severely impacted, and exposed dry lake bed could cause dust problems for miles into the Coachella and Imperial valleys.
State Secretary of Resources Mike Chrisman last spring chose a 75-year, $8.9 billion mitigation plan to restore the sea, ease air quality problems and preserve wildlife habitat.
A bill sponsored by state Sen. Denise Ducheny, D-San Diego, would earmark $47 million in state Proposition 84 water bond money for
The senator has also introduced a bill to form a governing structure for any sea restoration project, a mix of representatives from state and local agencies that Chrisman would oversee. #
http://search.mydesert.com/sp?aff=1100&skin=100&keywords=water&x=11&y=19
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